/* * ***************************************************************************** * * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2018-2024 Gavin D. Howard and contributors. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * ***************************************************************************** * * The parser for bc. * */ #if BC_ENABLED #include #include #include #include #include #include #include #include // Before you embark on trying to understand this code, have you read the // Development manual (manuals/development.md) and the comment in include/bc.h // yet? No? Do that first. I'm serious. // // The reason is because this file holds the most sensitive and finicky code in // the entire codebase. Even getting history to work on Windows was nothing // compared to this. This is where dreams go to die, where dragons live, and // from which Ken Thompson himself would flee. static void bc_parse_else(BcParse* p); static void bc_parse_stmt(BcParse* p); static BcParseStatus bc_parse_expr_err(BcParse* p, uint8_t flags, BcParseNext next); static void bc_parse_expr_status(BcParse* p, uint8_t flags, BcParseNext next); /** * Returns true if an instruction could only have come from a "leaf" expression. * For more on what leaf expressions are, read the comment for BC_PARSE_LEAF(). * @param t The instruction to test. * @return True if the instruction is a from a leaf expression. */ static bool bc_parse_inst_isLeaf(BcInst t) { return (t >= BC_INST_NUM && t <= BC_INST_LEADING_ZERO) || #if BC_ENABLE_EXTRA_MATH t == BC_INST_TRUNC || #endif // BC_ENABLE_EXTRA_MATH t <= BC_INST_DEC; } /** * Returns true if the *previous* token was a delimiter. A delimiter is anything * that can legally end a statement. In bc's case, it could be a newline, a * semicolon, and a brace in certain cases. * @param p The parser. * @return True if the token is a legal delimiter. */ static bool bc_parse_isDelimiter(const BcParse* p) { BcLexType t = p->l.t; bool good; // If it's an obvious delimiter, say so. if (BC_PARSE_DELIMITER(t)) return true; good = false; // If the current token is a keyword, then...beware. That means that we need // to check for a "dangling" else, where there was no brace-delimited block // on the previous if. if (t == BC_LEX_KW_ELSE) { size_t i; uint16_t *fptr = NULL, flags = BC_PARSE_FLAG_ELSE; // As long as going up the stack is valid for a dangling else, keep on. for (i = 0; i < p->flags.len && BC_PARSE_BLOCK_STMT(flags); ++i) { fptr = bc_vec_item_rev(&p->flags, i); flags = *fptr; // If we need a brace and don't have one, then we don't have a // delimiter. if ((flags & BC_PARSE_FLAG_BRACE) && p->l.last != BC_LEX_RBRACE) { return false; } } // Oh, and we had also better have an if statement somewhere. good = ((flags & BC_PARSE_FLAG_IF) != 0); } else if (t == BC_LEX_RBRACE) { size_t i; // Since we have a brace, we need to just check if a brace was needed. for (i = 0; !good && i < p->flags.len; ++i) { uint16_t* fptr = bc_vec_item_rev(&p->flags, i); good = (((*fptr) & BC_PARSE_FLAG_BRACE) != 0); } } return good; } /** * Returns true if we are in top level of a function body. The POSIX grammar * is defined such that anything is allowed after a function body, so we must * use this function to detect that case when ending a function body. * @param p The parser. * @return True if we are in the top level of parsing a function body. */ static bool bc_parse_TopFunc(const BcParse* p) { bool good = p->flags.len == 2; uint16_t val = BC_PARSE_FLAG_BRACE | BC_PARSE_FLAG_FUNC_INNER; val |= BC_PARSE_FLAG_FUNC; return good && BC_PARSE_TOP_FLAG(p) == val; } /** * Sets a previously defined exit label. What are labels? See the bc Parsing * section of the Development manual (manuals/development.md). * @param p The parser. */ static void bc_parse_setLabel(BcParse* p) { BcFunc* func = p->func; BcInstPtr* ip = bc_vec_top(&p->exits); size_t* label; assert(func == bc_vec_item(&p->prog->fns, p->fidx)); // Set the preallocated label to the correct index. label = bc_vec_item(&func->labels, ip->idx); *label = func->code.len; // Now, we don't need the exit label; it is done. bc_vec_pop(&p->exits); } /** * Creates a label and sets it to idx. If this is an exit label, then idx is * actually invalid, but it doesn't matter because it will be fixed by * bc_parse_setLabel() later. * @param p The parser. * @param idx The index of the label. */ static void bc_parse_createLabel(BcParse* p, size_t idx) { bc_vec_push(&p->func->labels, &idx); } /** * Creates a conditional label. Unlike an exit label, this label is set at * creation time because it comes *before* the code that will target it. * @param p The parser. * @param idx The index of the label. */ static void bc_parse_createCondLabel(BcParse* p, size_t idx) { bc_parse_createLabel(p, p->func->code.len); bc_vec_push(&p->conds, &idx); } /** * Creates an exit label to be filled in later by bc_parse_setLabel(). Also, why * create a label to be filled in later? Because exit labels are meant to be * targeted by code that comes *before* the label. Since we have to parse that * code first, and don't know how long it will be, we need to just make sure to * reserve a slot to be filled in later when we know. * * By the way, this uses BcInstPtr because it was convenient. The field idx * holds the index, and the field func holds the loop boolean. * * @param p The parser. * @param idx The index of the label's position. * @param loop True if the exit label is for a loop or not. */ static void bc_parse_createExitLabel(BcParse* p, size_t idx, bool loop) { BcInstPtr ip; assert(p->func == bc_vec_item(&p->prog->fns, p->fidx)); ip.func = loop; ip.idx = idx; ip.len = 0; bc_vec_push(&p->exits, &ip); bc_parse_createLabel(p, SIZE_MAX); } /** * Pops the correct operators off of the operator stack based on the current * operator. This is because of the Shunting-Yard algorithm. Lower prec means * higher precedence. * @param p The parser. * @param type The operator. * @param start The previous start of the operator stack. For more * information, see the bc Parsing section of the Development * manual (manuals/development.md). * @param nexprs A pointer to the current number of expressions that have not * been consumed yet. This is an IN and OUT parameter. */ static void bc_parse_operator(BcParse* p, BcLexType type, size_t start, size_t* nexprs) { BcLexType t; uchar l, r = BC_PARSE_OP_PREC(type); uchar left = BC_PARSE_OP_LEFT(type); // While we haven't hit the stop point yet... while (p->ops.len > start) { // Get the top operator. t = BC_PARSE_TOP_OP(p); // If it's a left paren, we have reached the end of whatever expression // this is no matter what. We also don't pop the left paren because it // will need to stay for the rest of the subexpression. if (t == BC_LEX_LPAREN) break; // Break for precedence. Precedence operates differently on left and // right associativity, by the way. A left associative operator that // matches the current precedence should take priority, but a right // associative operator should not. // // Also, a lower precedence value means a higher precedence. l = BC_PARSE_OP_PREC(t); if (l >= r && (l != r || !left)) break; // Do the housekeeping. In particular, make sure to note that one // expression was consumed (well, two were, but another was added) if // the operator was not a prefix operator. (Postfix operators are not // handled by this function at all.) bc_parse_push(p, BC_PARSE_TOKEN_INST(t)); bc_vec_pop(&p->ops); *nexprs -= !BC_PARSE_OP_PREFIX(t); } bc_vec_push(&p->ops, &type); } /** * Parses a right paren. In the Shunting-Yard algorithm, it needs to be put on * the operator stack. But before that, it needs to consume whatever operators * there are until it hits a left paren. * @param p The parser. * @param nexprs A pointer to the current number of expressions that have not * been consumed yet. This is an IN and OUT parameter. */ static void bc_parse_rightParen(BcParse* p, size_t* nexprs) { BcLexType top; // Consume operators until a left paren. while ((top = BC_PARSE_TOP_OP(p)) != BC_LEX_LPAREN) { bc_parse_push(p, BC_PARSE_TOKEN_INST(top)); bc_vec_pop(&p->ops); *nexprs -= !BC_PARSE_OP_PREFIX(top); } // We need to pop the left paren as well. bc_vec_pop(&p->ops); // Oh, and we also want the next token. bc_lex_next(&p->l); } /** * Parses function arguments. * @param p The parser. * @param flags Flags restricting what kind of expressions the arguments can * be. */ static void bc_parse_args(BcParse* p, uint8_t flags) { bool comma = false; size_t nargs; bc_lex_next(&p->l); // Print and comparison operators not allowed. Well, comparison operators // only for POSIX. But we do allow arrays, and we *must* get a value. flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL); flags |= (BC_PARSE_ARRAY | BC_PARSE_NEEDVAL); // Count the arguments and parse them. for (nargs = 0; p->l.t != BC_LEX_RPAREN; ++nargs) { bc_parse_expr_status(p, flags, bc_parse_next_arg); comma = (p->l.t == BC_LEX_COMMA); if (comma) bc_lex_next(&p->l); } // An ending comma is FAIL. if (BC_ERR(comma)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Now do the call with the number of arguments. bc_parse_push(p, BC_INST_CALL); bc_parse_pushIndex(p, nargs); } /** * Parses a function call. * @param p The parser. * @param flags Flags restricting what kind of expressions the arguments can * be. */ static void bc_parse_call(BcParse* p, const char* name, uint8_t flags) { size_t idx; bc_parse_args(p, flags); // We just assert this because bc_parse_args() should // ensure that the next token is what it should be. assert(p->l.t == BC_LEX_RPAREN); // We cannot use bc_program_insertFunc() here // because it will overwrite an existing function. idx = bc_map_index(&p->prog->fn_map, name); // The function does not exist yet. Create a space for it. If the user does // not define it, it's a *runtime* error, not a parse error. if (idx == BC_VEC_INVALID_IDX) { idx = bc_program_insertFunc(p->prog, name); assert(idx != BC_VEC_INVALID_IDX); // Make sure that this pointer was not invalidated. p->func = bc_vec_item(&p->prog->fns, p->fidx); } // The function exists, so set the right function index. else idx = ((BcId*) bc_vec_item(&p->prog->fn_map, idx))->idx; bc_parse_pushIndex(p, idx); // Make sure to get the next token. bc_lex_next(&p->l); } /** * Parses a name/identifier-based expression. It could be a variable, an array * element, an array itself (for function arguments), a function call, etc. * @param p The parser. * @param type A pointer to return the resulting instruction. * @param can_assign A pointer to return true if the name can be assigned to, * false otherwise. * @param flags Flags restricting what kind of expression the name can be. */ static void bc_parse_name(BcParse* p, BcInst* type, bool* can_assign, uint8_t flags) { char* name; BC_SIG_ASSERT_LOCKED; // We want a copy of the name since the lexer might overwrite its copy. name = bc_vm_strdup(p->l.str.v); BC_SETJMP_LOCKED(vm, err); // We need the next token to see if it's just a variable or something more. bc_lex_next(&p->l); // Array element or array. if (p->l.t == BC_LEX_LBRACKET) { bc_lex_next(&p->l); // Array only. This has to be a function parameter. if (p->l.t == BC_LEX_RBRACKET) { // Error if arrays are not allowed. if (BC_ERR(!(flags & BC_PARSE_ARRAY))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } *type = BC_INST_ARRAY; *can_assign = false; } else { // If we are here, we have an array element. We need to set the // expression parsing flags. uint8_t flags2 = (flags & ~(BC_PARSE_PRINT | BC_PARSE_REL)) | BC_PARSE_NEEDVAL; bc_parse_expr_status(p, flags2, bc_parse_next_elem); // The next token *must* be a right bracket. if (BC_ERR(p->l.t != BC_LEX_RBRACKET)) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } *type = BC_INST_ARRAY_ELEM; *can_assign = true; } // Make sure to get the next token. bc_lex_next(&p->l); // Push the instruction and the name of the identifier. bc_parse_push(p, *type); bc_parse_pushName(p, name, false); } else if (p->l.t == BC_LEX_LPAREN) { // We are parsing a function call; error if not allowed. if (BC_ERR(flags & BC_PARSE_NOCALL)) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } *type = BC_INST_CALL; *can_assign = false; bc_parse_call(p, name, flags); } else { // Just a variable. *type = BC_INST_VAR; *can_assign = true; bc_parse_push(p, BC_INST_VAR); bc_parse_pushName(p, name, true); } err: // Need to make sure to unallocate the name. free(name); BC_LONGJMP_CONT(vm); BC_SIG_MAYLOCK; } /** * Parses a builtin function that takes no arguments. This includes read(), * rand(), maxibase(), maxobase(), maxscale(), and maxrand(). * @param p The parser. * @param inst The instruction corresponding to the builtin. */ static void bc_parse_noArgBuiltin(BcParse* p, BcInst inst) { // Must have a left paren. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Must have a right paren. bc_lex_next(&p->l); if ((p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_parse_push(p, inst); bc_lex_next(&p->l); } /** * Parses a builtin function that takes 1 argument. This includes length(), * sqrt(), abs(), scale(), and irand(). * @param p The parser. * @param type The lex token. * @param flags The expression parsing flags for parsing the argument. * @param prev An out parameter; the previous instruction pointer. */ static void bc_parse_builtin(BcParse* p, BcLexType type, uint8_t flags, BcInst* prev) { // Must have a left paren. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Change the flags as needed for parsing the argument. flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL); flags |= BC_PARSE_NEEDVAL; // Since length can take arrays, we need to specially add that flag. if (type == BC_LEX_KW_LENGTH || type == BC_LEX_KW_ASCIIFY) { flags |= BC_PARSE_ARRAY; } // Otherwise, we need to clear it because it could be set. else flags &= ~(BC_PARSE_ARRAY); bc_parse_expr_status(p, flags, bc_parse_next_rel); // Must have a right paren. if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Adjust previous based on the token and push it. *prev = type - BC_LEX_KW_LENGTH + BC_INST_LENGTH; bc_parse_push(p, *prev); bc_lex_next(&p->l); } /** * Parses a builtin function that takes 3 arguments. This includes modexp() and * divmod(). * @param p The parser. * @param type The lex token. * @param flags The expression parsing flags for parsing the argument. * @param prev An out parameter; the previous instruction pointer. */ static void bc_parse_builtin3(BcParse* p, BcLexType type, uint8_t flags, BcInst* prev) { assert(type == BC_LEX_KW_MODEXP || type == BC_LEX_KW_DIVMOD); // Must have a left paren. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Change the flags as needed for parsing the argument. flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL); flags |= BC_PARSE_NEEDVAL; bc_parse_expr_status(p, flags, bc_parse_next_builtin); // Must have a comma. if (BC_ERR(p->l.t != BC_LEX_COMMA)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); bc_parse_expr_status(p, flags, bc_parse_next_builtin); // Must have a comma. if (BC_ERR(p->l.t != BC_LEX_COMMA)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // If it is a divmod, parse an array name. Otherwise, just parse another // expression. if (type == BC_LEX_KW_DIVMOD) { // Must have a name. if (BC_ERR(p->l.t != BC_LEX_NAME)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // This is safe because the next token should not overwrite the name. bc_lex_next(&p->l); // Must have a left bracket. if (BC_ERR(p->l.t != BC_LEX_LBRACKET)) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } // This is safe because the next token should not overwrite the name. bc_lex_next(&p->l); // Must have a right bracket. if (BC_ERR(p->l.t != BC_LEX_RBRACKET)) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } // This is safe because the next token should not overwrite the name. bc_lex_next(&p->l); } else bc_parse_expr_status(p, flags, bc_parse_next_rel); // Must have a right paren. if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Adjust previous based on the token and push it. *prev = type - BC_LEX_KW_MODEXP + BC_INST_MODEXP; bc_parse_push(p, *prev); // If we have divmod, we need to assign the modulus to the array element, so // we need to push the instructions for doing so. if (type == BC_LEX_KW_DIVMOD) { // The zeroth element. bc_parse_push(p, BC_INST_ZERO); bc_parse_push(p, BC_INST_ARRAY_ELEM); // Push the array. bc_parse_pushName(p, p->l.str.v, false); // Swap them and assign. After this, the top item on the stack should // be the quotient. bc_parse_push(p, BC_INST_SWAP); bc_parse_push(p, BC_INST_ASSIGN_NO_VAL); } bc_lex_next(&p->l); } /** * Parses the scale keyword. This is special because scale can be a value or a * builtin function. * @param p The parser. * @param type An out parameter; the instruction for the parse. * @param can_assign An out parameter; whether the expression can be assigned * to. * @param flags The expression parsing flags for parsing a scale() arg. */ static void bc_parse_scale(BcParse* p, BcInst* type, bool* can_assign, uint8_t flags) { bc_lex_next(&p->l); // Without the left paren, it's just the keyword. if (p->l.t != BC_LEX_LPAREN) { // Set, push, and return. *type = BC_INST_SCALE; *can_assign = true; bc_parse_push(p, BC_INST_SCALE); return; } // Handle the scale function. *type = BC_INST_SCALE_FUNC; *can_assign = false; // Once again, adjust the flags. flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL); flags |= BC_PARSE_NEEDVAL; bc_lex_next(&p->l); bc_parse_expr_status(p, flags, bc_parse_next_rel); // Must have a right paren. if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_parse_push(p, BC_INST_SCALE_FUNC); bc_lex_next(&p->l); } /** * Parses and increment or decrement operator. This is a bit complex. * @param p The parser. * @param prev An out parameter; the previous instruction pointer. * @param can_assign An out parameter; whether the expression can be assigned * to. * @param nexs An in/out parameter; the number of expressions in the * parse tree that are not used. * @param flags The expression parsing flags for parsing a scale() arg. */ static void bc_parse_incdec(BcParse* p, BcInst* prev, bool* can_assign, size_t* nexs, uint8_t flags) { BcLexType type; uchar inst; BcInst etype = *prev; BcLexType last = p->l.last; assert(prev != NULL && can_assign != NULL); // If we can't assign to the previous token, then we have an error. if (BC_ERR(last == BC_LEX_OP_INC || last == BC_LEX_OP_DEC || last == BC_LEX_RPAREN)) { bc_parse_err(p, BC_ERR_PARSE_ASSIGN); } // Is the previous instruction for a variable? if (BC_PARSE_INST_VAR(etype)) { // If so, this is a postfix operator. if (!*can_assign) bc_parse_err(p, BC_ERR_PARSE_ASSIGN); // Only postfix uses BC_INST_INC and BC_INST_DEC. *prev = inst = BC_INST_INC + (p->l.t != BC_LEX_OP_INC); bc_parse_push(p, inst); bc_lex_next(&p->l); *can_assign = false; } else { // This is a prefix operator. In that case, we just convert it to // an assignment instruction. *prev = inst = BC_INST_ASSIGN_PLUS + (p->l.t != BC_LEX_OP_INC); bc_lex_next(&p->l); type = p->l.t; // Because we parse the next part of the expression // right here, we need to increment this. *nexs = *nexs + 1; // Is the next token a normal identifier? if (type == BC_LEX_NAME) { // Parse the name. uint8_t flags2 = flags & ~(BC_PARSE_ARRAY); bc_parse_name(p, prev, can_assign, flags2 | BC_PARSE_NOCALL); } // Is the next token a global? else if (type >= BC_LEX_KW_LAST && type <= BC_LEX_KW_OBASE) { bc_parse_push(p, type - BC_LEX_KW_LAST + BC_INST_LAST); bc_lex_next(&p->l); } // Is the next token specifically scale, which needs special treatment? else if (BC_NO_ERR(type == BC_LEX_KW_SCALE)) { bc_lex_next(&p->l); // Check that scale() was not used. if (BC_ERR(p->l.t == BC_LEX_LPAREN)) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } else bc_parse_push(p, BC_INST_SCALE); } // Now we know we have an error. else bc_parse_err(p, BC_ERR_PARSE_TOKEN); *can_assign = false; bc_parse_push(p, BC_INST_ONE); bc_parse_push(p, inst); } } /** * Parses the minus operator. This needs special treatment because it is either * subtract or negation. * @param p The parser. * @param prev An in/out parameter; the previous instruction. * @param ops_bgn The size of the operator stack. * @param rparen True if the last token was a right paren. * @param binlast True if the last token was a binary operator. * @param nexprs An in/out parameter; the number of unused expressions. */ static void bc_parse_minus(BcParse* p, BcInst* prev, size_t ops_bgn, bool rparen, bool binlast, size_t* nexprs) { BcLexType type; bc_lex_next(&p->l); // Figure out if it's a minus or a negation. type = BC_PARSE_LEAF(*prev, binlast, rparen) ? BC_LEX_OP_MINUS : BC_LEX_NEG; *prev = BC_PARSE_TOKEN_INST(type); // We can just push onto the op stack because this is the largest // precedence operator that gets pushed. Inc/dec does not. if (type != BC_LEX_OP_MINUS) bc_vec_push(&p->ops, &type); else bc_parse_operator(p, type, ops_bgn, nexprs); } /** * Parses a string. * @param p The parser. * @param inst The instruction corresponding to how the string was found and * how it should be printed. */ static void bc_parse_str(BcParse* p, BcInst inst) { bc_parse_addString(p); bc_parse_push(p, inst); bc_lex_next(&p->l); } /** * Parses a print statement. * @param p The parser. */ static void bc_parse_print(BcParse* p, BcLexType type) { BcLexType t; bool comma = false; BcInst inst = type == BC_LEX_KW_STREAM ? BC_INST_PRINT_STREAM : BC_INST_PRINT_POP; bc_lex_next(&p->l); t = p->l.t; // A print or stream statement has to have *something*. if (bc_parse_isDelimiter(p)) bc_parse_err(p, BC_ERR_PARSE_PRINT); do { // If the token is a string, then print it with escapes. // BC_INST_PRINT_POP plays that role for bc. if (t == BC_LEX_STR) bc_parse_str(p, inst); else { // We have an actual number; parse and add a print instruction. bc_parse_expr_status(p, BC_PARSE_NEEDVAL, bc_parse_next_print); bc_parse_push(p, inst); } // Is the next token a comma? comma = (p->l.t == BC_LEX_COMMA); // Get the next token if we have a comma. if (comma) bc_lex_next(&p->l); else { // If we don't have a comma, the statement needs to end. if (!bc_parse_isDelimiter(p)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); else break; } t = p->l.t; } while (true); // If we have a comma but no token, that's bad. if (BC_ERR(comma)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); } /** * Parses a return statement. * @param p The parser. */ static void bc_parse_return(BcParse* p) { BcLexType t; bool paren; uchar inst = BC_INST_RET0; // If we are not in a function, that's an error. if (BC_ERR(!BC_PARSE_FUNC(p))) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // If we are in a void function, make sure to return void. if (p->func->voidfn) inst = BC_INST_RET_VOID; bc_lex_next(&p->l); t = p->l.t; paren = (t == BC_LEX_LPAREN); // An empty return statement just needs to push the selected instruction. if (bc_parse_isDelimiter(p)) bc_parse_push(p, inst); else { BcParseStatus s; // Need to parse the expression whose value will be returned. s = bc_parse_expr_err(p, BC_PARSE_NEEDVAL, bc_parse_next_expr); // If the expression was empty, just push the selected instruction. if (s == BC_PARSE_STATUS_EMPTY_EXPR) { bc_parse_push(p, inst); bc_lex_next(&p->l); } // POSIX requires parentheses. if (!paren || p->l.last != BC_LEX_RPAREN) { bc_parse_err(p, BC_ERR_POSIX_RET); } // Void functions require an empty expression. if (BC_ERR(p->func->voidfn)) { if (s != BC_PARSE_STATUS_EMPTY_EXPR) { bc_parse_verr(p, BC_ERR_PARSE_RET_VOID, p->func->name); } } // If we got here, we want to be sure to end the function with a real // return instruction, just in case. else bc_parse_push(p, BC_INST_RET); } } /** * Clears flags that indicate the end of an if statement and its block and sets * the jump location. * @param p The parser. */ static void bc_parse_noElse(BcParse* p) { uint16_t* flag_ptr = BC_PARSE_TOP_FLAG_PTR(p); *flag_ptr = (*flag_ptr & ~(BC_PARSE_FLAG_IF_END)); bc_parse_setLabel(p); } /** * Ends (finishes parsing) the body of a control statement or a function. * @param p The parser. * @param brace True if the body was ended by a brace, false otherwise. */ static void bc_parse_endBody(BcParse* p, bool brace) { bool has_brace, new_else = false; // We cannot be ending a body if there are no bodies to end. if (BC_ERR(p->flags.len <= 1)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); if (brace) { // The brace was already gotten; make sure that the caller did not lie. // We check for the requirement of braces later. assert(p->l.t == BC_LEX_RBRACE); bc_lex_next(&p->l); // If the next token is not a delimiter, that is a problem. if (BC_ERR(!bc_parse_isDelimiter(p) && !bc_parse_TopFunc(p))) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } } // Do we have a brace flag? has_brace = (BC_PARSE_BRACE(p) != 0); do { size_t len = p->flags.len; bool loop; // If we have a brace flag but not a brace, that's a problem. if (has_brace && !brace) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Are we inside a loop? loop = (BC_PARSE_LOOP_INNER(p) != 0); // If we are ending a loop or an else... if (loop || BC_PARSE_ELSE(p)) { // Loops have condition labels that we have to take care of as well. if (loop) { size_t* label = bc_vec_top(&p->conds); bc_parse_push(p, BC_INST_JUMP); bc_parse_pushIndex(p, *label); bc_vec_pop(&p->conds); } bc_parse_setLabel(p); bc_vec_pop(&p->flags); } // If we are ending a function... else if (BC_PARSE_FUNC_INNER(p)) { BcInst inst = (p->func->voidfn ? BC_INST_RET_VOID : BC_INST_RET0); bc_parse_push(p, inst); bc_parse_updateFunc(p, BC_PROG_MAIN); bc_vec_pop(&p->flags); } // If we have a brace flag and not an if statement, we can pop the top // of the flags stack because they have been taken care of above. else if (has_brace && !BC_PARSE_IF(p)) bc_vec_pop(&p->flags); // This needs to be last to parse nested if's properly. if (BC_PARSE_IF(p) && (len == p->flags.len || !BC_PARSE_BRACE(p))) { // Eat newlines. while (p->l.t == BC_LEX_NLINE) { bc_lex_next(&p->l); } // *Now* we can pop the flags. bc_vec_pop(&p->flags); // If we are allowed non-POSIX stuff... if (!BC_S) { // Have we found yet another dangling else? *(BC_PARSE_TOP_FLAG_PTR(p)) |= BC_PARSE_FLAG_IF_END; new_else = (p->l.t == BC_LEX_KW_ELSE); // Parse the else or end the if statement body. if (new_else) bc_parse_else(p); else if (!has_brace && (!BC_PARSE_IF_END(p) || brace)) { bc_parse_noElse(p); } } // POSIX requires us to do the bare minimum only. else bc_parse_noElse(p); } // If these are both true, we have "used" the braces that we found. if (brace && has_brace) brace = false; } // This condition was perhaps the hardest single part of the parser. If // the flags stack does not have enough, we should stop. If we have a // new else statement, we should stop. If we do have the end of an if // statement and we have eaten the brace, we should stop. If we do have // a brace flag, we should stop. while (p->flags.len > 1 && !new_else && (!BC_PARSE_IF_END(p) || brace) && !(has_brace = (BC_PARSE_BRACE(p) != 0))); // If we have a brace, yet no body for it, that's a problem. if (BC_ERR(p->flags.len == 1 && brace)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); else if (brace && BC_PARSE_BRACE(p)) { // If we make it here, we have a brace and a flag for it. uint16_t flags = BC_PARSE_TOP_FLAG(p); // This condition ensure that the *last* body is correctly finished by // popping its flags. if (!(flags & (BC_PARSE_FLAG_FUNC_INNER | BC_PARSE_FLAG_LOOP_INNER)) && !(flags & (BC_PARSE_FLAG_IF | BC_PARSE_FLAG_ELSE)) && !(flags & (BC_PARSE_FLAG_IF_END))) { bc_vec_pop(&p->flags); } } } /** * Starts the body of a control statement or function. * @param p The parser. * @param flags The current flags (will be edited). */ static void bc_parse_startBody(BcParse* p, uint16_t flags) { assert(flags); flags |= (BC_PARSE_TOP_FLAG(p) & (BC_PARSE_FLAG_FUNC | BC_PARSE_FLAG_LOOP)); flags |= BC_PARSE_FLAG_BODY; bc_vec_push(&p->flags, &flags); } void bc_parse_endif(BcParse* p) { size_t i; bool good; // Not a problem if this is true. if (BC_NO_ERR(!BC_PARSE_NO_EXEC(p))) return; good = true; // Find an instance of a body that needs closing, i.e., a statement that did // not have a right brace when it should have. for (i = 0; good && i < p->flags.len; ++i) { uint16_t flag = *((uint16_t*) bc_vec_item(&p->flags, i)); good = ((flag & BC_PARSE_FLAG_BRACE) != BC_PARSE_FLAG_BRACE); } // If we did not find such an instance... if (good) { // We set this to restore it later. We don't want the parser thinking // that we are on stdin for this one because it will want more. BcMode mode = vm->mode; vm->mode = BC_MODE_FILE; // End all of the if statements and loops. while (p->flags.len > 1 || BC_PARSE_IF_END(p)) { if (BC_PARSE_IF_END(p)) bc_parse_noElse(p); if (p->flags.len > 1) bc_parse_endBody(p, false); } vm->mode = (uchar) mode; } // If we reach here, a block was not properly closed, and we should error. else bc_parse_err(&vm->prs, BC_ERR_PARSE_BLOCK); } /** * Parses an if statement. * @param p The parser. */ static void bc_parse_if(BcParse* p) { // We are allowed relational operators, and we must have a value. size_t idx; uint8_t flags = (BC_PARSE_REL | BC_PARSE_NEEDVAL); // Get the left paren and barf if necessary. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Parse the condition. bc_lex_next(&p->l); bc_parse_expr_status(p, flags, bc_parse_next_rel); // Must have a right paren. if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Insert the conditional jump instruction. bc_parse_push(p, BC_INST_JUMP_ZERO); idx = p->func->labels.len; // Push the index for the instruction and create an exit label for an else // statement. bc_parse_pushIndex(p, idx); bc_parse_createExitLabel(p, idx, false); bc_parse_startBody(p, BC_PARSE_FLAG_IF); } /** * Parses an else statement. * @param p The parser. */ static void bc_parse_else(BcParse* p) { size_t idx = p->func->labels.len; // We must be at the end of an if statement. if (BC_ERR(!BC_PARSE_IF_END(p))) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Push an unconditional jump to make bc jump over the else statement if it // executed the original if statement. bc_parse_push(p, BC_INST_JUMP); bc_parse_pushIndex(p, idx); // Clear the else stuff. Yes, that function is misnamed for its use here, // but deal with it. bc_parse_noElse(p); // Create the exit label and parse the body. bc_parse_createExitLabel(p, idx, false); bc_parse_startBody(p, BC_PARSE_FLAG_ELSE); bc_lex_next(&p->l); } /** * Parse a while loop. * @param p The parser. */ static void bc_parse_while(BcParse* p) { // We are allowed relational operators, and we must have a value. size_t idx; uint8_t flags = (BC_PARSE_REL | BC_PARSE_NEEDVAL); // Get the left paren and barf if necessary. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Create the labels. Loops need both. bc_parse_createCondLabel(p, p->func->labels.len); idx = p->func->labels.len; bc_parse_createExitLabel(p, idx, true); // Parse the actual condition and barf on non-right paren. bc_parse_expr_status(p, flags, bc_parse_next_rel); if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Now we can push the conditional jump and start the body. bc_parse_push(p, BC_INST_JUMP_ZERO); bc_parse_pushIndex(p, idx); bc_parse_startBody(p, BC_PARSE_FLAG_LOOP | BC_PARSE_FLAG_LOOP_INNER); } /** * Parse a for loop. * @param p The parser. */ static void bc_parse_for(BcParse* p) { size_t cond_idx, exit_idx, body_idx, update_idx; // Barf on the missing left paren. bc_lex_next(&p->l); if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // The first statement can be empty, but if it is, check for error in POSIX // mode. Otherwise, parse it. if (p->l.t != BC_LEX_SCOLON) bc_parse_expr_status(p, 0, bc_parse_next_for); else bc_parse_err(p, BC_ERR_POSIX_FOR); // Must have a semicolon. if (BC_ERR(p->l.t != BC_LEX_SCOLON)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // These are indices for labels. There are so many of them because the end // of the loop must unconditionally jump to the update code. Then the update // code must unconditionally jump to the condition code. Then the condition // code must *conditionally* jump to the exit. cond_idx = p->func->labels.len; update_idx = cond_idx + 1; body_idx = update_idx + 1; exit_idx = body_idx + 1; // This creates the condition label. bc_parse_createLabel(p, p->func->code.len); // Parse an expression if it exists. if (p->l.t != BC_LEX_SCOLON) { uint8_t flags = (BC_PARSE_REL | BC_PARSE_NEEDVAL); bc_parse_expr_status(p, flags, bc_parse_next_for); } else { // Set this for the next call to bc_parse_number because an empty // condition means that it is an infinite loop, so the condition must be // non-zero. This is safe to set because the current token is a // semicolon, which has no string requirement. bc_vec_string(&p->l.str, sizeof(bc_parse_one) - 1, bc_parse_one); bc_parse_number(p); // An empty condition makes POSIX mad. bc_parse_err(p, BC_ERR_POSIX_FOR); } // Must have a semicolon. if (BC_ERR(p->l.t != BC_LEX_SCOLON)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); // Now we can set up the conditional jump to the exit and an unconditional // jump to the body right after. The unconditional jump to the body is // because there is update code coming right after the condition, so we need // to skip it to get to the body. bc_parse_push(p, BC_INST_JUMP_ZERO); bc_parse_pushIndex(p, exit_idx); bc_parse_push(p, BC_INST_JUMP); bc_parse_pushIndex(p, body_idx); // Now create the label for the update code. bc_parse_createCondLabel(p, update_idx); // Parse if not empty, and if it is, let POSIX yell if necessary. if (p->l.t != BC_LEX_RPAREN) bc_parse_expr_status(p, 0, bc_parse_next_rel); else bc_parse_err(p, BC_ERR_POSIX_FOR); // Must have a right paren. if (BC_ERR(p->l.t != BC_LEX_RPAREN)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Set up a jump to the condition right after the update code. bc_parse_push(p, BC_INST_JUMP); bc_parse_pushIndex(p, cond_idx); bc_parse_createLabel(p, p->func->code.len); // Create an exit label for the body and start the body. bc_parse_createExitLabel(p, exit_idx, true); bc_lex_next(&p->l); bc_parse_startBody(p, BC_PARSE_FLAG_LOOP | BC_PARSE_FLAG_LOOP_INNER); } /** * Parse a statement or token that indicates a loop exit. This includes an * actual loop exit, the break keyword, or the continue keyword. * @param p The parser. * @param type The type of exit. */ static void bc_parse_loopExit(BcParse* p, BcLexType type) { size_t i; BcInstPtr* ip; // Must have a loop. If we don't, that's an error. if (BC_ERR(!BC_PARSE_LOOP(p))) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // If we have a break statement... if (type == BC_LEX_KW_BREAK) { // If there are no exits, something went wrong somewhere. if (BC_ERR(!p->exits.len)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); // Get the exit. i = p->exits.len - 1; ip = bc_vec_item(&p->exits, i); // The condition !ip->func is true if the exit is not for a loop, so we // need to find the first actual loop exit. while (!ip->func && i < p->exits.len) { ip = bc_vec_item(&p->exits, i); i -= 1; } // Make sure everything is hunky dory. assert(ip != NULL && (i < p->exits.len || ip->func)); // Set the index for the exit. i = ip->idx; } // If we have a continue statement or just the loop end, jump to the // condition (or update for a foor loop). else i = *((size_t*) bc_vec_top(&p->conds)); // Add the unconditional jump. bc_parse_push(p, BC_INST_JUMP); bc_parse_pushIndex(p, i); bc_lex_next(&p->l); } /** * Parse a function (header). * @param p The parser. */ static void bc_parse_func(BcParse* p) { bool comma = false, voidfn; uint16_t flags; size_t idx; bc_lex_next(&p->l); // Must have a name. if (BC_ERR(p->l.t != BC_LEX_NAME)) bc_parse_err(p, BC_ERR_PARSE_FUNC); // If the name is "void", and POSIX is not on, mark as void. voidfn = (!BC_IS_POSIX && p->l.t == BC_LEX_NAME && !strcmp(p->l.str.v, "void")); // We can safely do this because the expected token should not overwrite the // function name. bc_lex_next(&p->l); // If we *don't* have another name, then void is the name of the function. voidfn = (voidfn && p->l.t == BC_LEX_NAME); // With a void function, allow POSIX to complain and get a new token. if (voidfn) { bc_parse_err(p, BC_ERR_POSIX_VOID); // We can safely do this because the expected token should not overwrite // the function name. bc_lex_next(&p->l); } // Must have a left paren. if (BC_ERR(p->l.t != BC_LEX_LPAREN)) bc_parse_err(p, BC_ERR_PARSE_FUNC); // Make sure the functions map and vector are synchronized. assert(p->prog->fns.len == p->prog->fn_map.len); // Insert the function by name into the map and vector. idx = bc_program_insertFunc(p->prog, p->l.str.v); // Make sure the insert worked. assert(idx); // Update the function pointer and stuff in the parser and set its void. bc_parse_updateFunc(p, idx); p->func->voidfn = voidfn; bc_lex_next(&p->l); // While we do not have a right paren, we are still parsing arguments. while (p->l.t != BC_LEX_RPAREN) { BcType t = BC_TYPE_VAR; // If we have an asterisk, we are parsing a reference argument. if (p->l.t == BC_LEX_OP_MULTIPLY) { t = BC_TYPE_REF; bc_lex_next(&p->l); // Let POSIX complain if necessary. bc_parse_err(p, BC_ERR_POSIX_REF); } // If we don't have a name, the argument will not have a name. Barf. if (BC_ERR(p->l.t != BC_LEX_NAME)) bc_parse_err(p, BC_ERR_PARSE_FUNC); // Increment the number of parameters. p->func->nparams += 1; // Copy the string in the lexer so that we can use the lexer again. bc_vec_string(&p->buf, p->l.str.len, p->l.str.v); bc_lex_next(&p->l); // We are parsing an array parameter if this is true. if (p->l.t == BC_LEX_LBRACKET) { // Set the array type, unless we are already parsing a reference. if (t == BC_TYPE_VAR) t = BC_TYPE_ARRAY; bc_lex_next(&p->l); // The brackets *must* be empty. if (BC_ERR(p->l.t != BC_LEX_RBRACKET)) { bc_parse_err(p, BC_ERR_PARSE_FUNC); } bc_lex_next(&p->l); } // If we did *not* get a bracket, but we are expecting a reference, we // have a problem. else if (BC_ERR(t == BC_TYPE_REF)) { bc_parse_verr(p, BC_ERR_PARSE_REF_VAR, p->buf.v); } // Test for comma and get the next token if it exists. comma = (p->l.t == BC_LEX_COMMA); if (comma) bc_lex_next(&p->l); // Insert the parameter into the function. bc_func_insert(p->func, p->prog, p->buf.v, t, p->l.line); } // If we have a comma, but no parameter, barf. if (BC_ERR(comma)) bc_parse_err(p, BC_ERR_PARSE_FUNC); // Start the body. flags = BC_PARSE_FLAG_FUNC | BC_PARSE_FLAG_FUNC_INNER; bc_parse_startBody(p, flags); bc_lex_next(&p->l); // POSIX requires that a brace be on the same line as the function header. // If we don't have a brace, let POSIX throw an error. if (p->l.t != BC_LEX_LBRACE) bc_parse_err(p, BC_ERR_POSIX_BRACE); } /** * Parse an auto list. * @param p The parser. */ static void bc_parse_auto(BcParse* p) { bool comma, one; // Error if the auto keyword appeared in the wrong place. if (BC_ERR(!p->auto_part)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); bc_lex_next(&p->l); p->auto_part = comma = false; // We need at least one variable or array. one = (p->l.t == BC_LEX_NAME); // While we have a variable or array. while (p->l.t == BC_LEX_NAME) { BcType t; // Copy the name from the lexer, so we can use it again. bc_vec_string(&p->buf, p->l.str.len - 1, p->l.str.v); bc_lex_next(&p->l); // If we are parsing an array... if (p->l.t == BC_LEX_LBRACKET) { t = BC_TYPE_ARRAY; bc_lex_next(&p->l); // The brackets *must* be empty. if (BC_ERR(p->l.t != BC_LEX_RBRACKET)) { bc_parse_err(p, BC_ERR_PARSE_FUNC); } bc_lex_next(&p->l); } else t = BC_TYPE_VAR; // Test for comma and get the next token if it exists. comma = (p->l.t == BC_LEX_COMMA); if (comma) bc_lex_next(&p->l); // Insert the auto into the function. bc_func_insert(p->func, p->prog, p->buf.v, t, p->l.line); } // If we have a comma, but no auto, barf. if (BC_ERR(comma)) bc_parse_err(p, BC_ERR_PARSE_FUNC); // If we don't have any variables or arrays, barf. if (BC_ERR(!one)) bc_parse_err(p, BC_ERR_PARSE_NO_AUTO); // The auto statement should be all that's in the statement. if (BC_ERR(!bc_parse_isDelimiter(p))) bc_parse_err(p, BC_ERR_PARSE_TOKEN); } /** * Parses a body. * @param p The parser. * @param brace True if a brace was encountered, false otherwise. */ static void bc_parse_body(BcParse* p, bool brace) { uint16_t* flag_ptr = BC_PARSE_TOP_FLAG_PTR(p); assert(flag_ptr != NULL); assert(p->flags.len >= 2); // The body flag is for when we expect a body. We got a body, so clear the // flag. *flag_ptr &= ~(BC_PARSE_FLAG_BODY); // If we are inside a function, that means we just barely entered it, and // we can expect an auto list. if (*flag_ptr & BC_PARSE_FLAG_FUNC_INNER) { // We *must* have a brace in this case. if (BC_ERR(!brace)) bc_parse_err(p, BC_ERR_PARSE_TOKEN); p->auto_part = (p->l.t != BC_LEX_KW_AUTO); if (!p->auto_part) { // Make sure this is true to not get a parse error. p->auto_part = true; // Since we already have the auto keyword, parse. bc_parse_auto(p); } // Eat a newline. if (p->l.t == BC_LEX_NLINE) bc_lex_next(&p->l); } else { // This is the easy part. size_t len = p->flags.len; assert(*flag_ptr); // Parse a statement. bc_parse_stmt(p); // This is a very important condition to get right. If there is no // brace, and no body flag, and the flags len hasn't shrunk, then we // have a body that was not delimited by braces, so we need to end it // now, after just one statement. if (!brace && !BC_PARSE_BODY(p) && len <= p->flags.len) { bc_parse_endBody(p, false); } } } /** * Parses a statement. This is the entry point for just about everything, except * function definitions. * @param p The parser. */ static void bc_parse_stmt(BcParse* p) { size_t len; uint16_t flags; BcLexType type = p->l.t; // Eat newline. if (type == BC_LEX_NLINE) { bc_lex_next(&p->l); return; } // Eat auto list. if (type == BC_LEX_KW_AUTO) { bc_parse_auto(p); return; } // If we reach this point, no auto list is allowed. p->auto_part = false; // Everything but an else needs to be taken care of here, but else is // special. if (type != BC_LEX_KW_ELSE) { // After an if, no else found. if (BC_PARSE_IF_END(p)) { // Clear the expectation for else, end body, and return. Returning // gives us a clean slate for parsing again. bc_parse_noElse(p); if (p->flags.len > 1 && !BC_PARSE_BRACE(p)) { bc_parse_endBody(p, false); } return; } // With a left brace, we are parsing a body. else if (type == BC_LEX_LBRACE) { // We need to start a body if we are not expecting one yet. if (!BC_PARSE_BODY(p)) { bc_parse_startBody(p, BC_PARSE_FLAG_BRACE); bc_lex_next(&p->l); } // If we *are* expecting a body, that body should get a brace. This // takes care of braces being on a different line than if and loop // headers. else { *(BC_PARSE_TOP_FLAG_PTR(p)) |= BC_PARSE_FLAG_BRACE; bc_lex_next(&p->l); bc_parse_body(p, true); } // If we have reached this point, we need to return for a clean // slate. return; } // This happens when we are expecting a body and get a single statement, // i.e., a body with no braces surrounding it. Returns after for a clean // slate. else if (BC_PARSE_BODY(p) && !BC_PARSE_BRACE(p)) { bc_parse_body(p, false); return; } } len = p->flags.len; flags = BC_PARSE_TOP_FLAG(p); switch (type) { // All of these are valid for expressions. case BC_LEX_OP_INC: case BC_LEX_OP_DEC: case BC_LEX_OP_MINUS: case BC_LEX_OP_BOOL_NOT: case BC_LEX_LPAREN: case BC_LEX_NAME: case BC_LEX_NUMBER: case BC_LEX_KW_IBASE: case BC_LEX_KW_LAST: case BC_LEX_KW_LENGTH: case BC_LEX_KW_OBASE: case BC_LEX_KW_SCALE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_SEED: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_SQRT: case BC_LEX_KW_ABS: case BC_LEX_KW_IS_NUMBER: case BC_LEX_KW_IS_STRING: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_IRAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_ASCIIFY: case BC_LEX_KW_MODEXP: case BC_LEX_KW_DIVMOD: case BC_LEX_KW_READ: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_RAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_MAXIBASE: case BC_LEX_KW_MAXOBASE: case BC_LEX_KW_MAXSCALE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_MAXRAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_LINE_LENGTH: case BC_LEX_KW_GLOBAL_STACKS: case BC_LEX_KW_LEADING_ZERO: { bc_parse_expr_status(p, BC_PARSE_PRINT, bc_parse_next_expr); break; } case BC_LEX_KW_ELSE: { bc_parse_else(p); break; } // Just eat. case BC_LEX_SCOLON: { // Do nothing. break; } case BC_LEX_RBRACE: { bc_parse_endBody(p, true); break; } case BC_LEX_STR: { bc_parse_str(p, BC_INST_PRINT_STR); break; } case BC_LEX_KW_BREAK: case BC_LEX_KW_CONTINUE: { bc_parse_loopExit(p, p->l.t); break; } case BC_LEX_KW_FOR: { bc_parse_for(p); break; } case BC_LEX_KW_HALT: { bc_parse_push(p, BC_INST_HALT); bc_lex_next(&p->l); break; } case BC_LEX_KW_IF: { bc_parse_if(p); break; } case BC_LEX_KW_LIMITS: { // `limits` is a compile-time command, so execute it right away. bc_vm_printf("BC_LONG_BIT = %lu\n", (ulong) BC_LONG_BIT); bc_vm_printf("BC_BASE_DIGS = %lu\n", (ulong) BC_BASE_DIGS); bc_vm_printf("BC_BASE_POW = %lu\n", (ulong) BC_BASE_POW); bc_vm_printf("BC_OVERFLOW_MAX = %lu\n", (ulong) BC_NUM_BIGDIG_MAX); bc_vm_printf("\n"); bc_vm_printf("BC_BASE_MAX = %lu\n", BC_MAX_OBASE); bc_vm_printf("BC_DIM_MAX = %lu\n", BC_MAX_DIM); bc_vm_printf("BC_SCALE_MAX = %lu\n", BC_MAX_SCALE); bc_vm_printf("BC_STRING_MAX = %lu\n", BC_MAX_STRING); bc_vm_printf("BC_NAME_MAX = %lu\n", BC_MAX_NAME); bc_vm_printf("BC_NUM_MAX = %lu\n", BC_MAX_NUM); #if BC_ENABLE_EXTRA_MATH bc_vm_printf("BC_RAND_MAX = %lu\n", BC_MAX_RAND); #endif // BC_ENABLE_EXTRA_MATH bc_vm_printf("MAX Exponent = %lu\n", BC_MAX_EXP); bc_vm_printf("Number of vars = %lu\n", BC_MAX_VARS); bc_lex_next(&p->l); break; } case BC_LEX_KW_STREAM: case BC_LEX_KW_PRINT: { bc_parse_print(p, type); break; } case BC_LEX_KW_QUIT: { // Quit is a compile-time command. We don't exit directly, so the vm // can clean up. vm->status = BC_STATUS_QUIT; BC_JMP; break; } case BC_LEX_KW_RETURN: { bc_parse_return(p); break; } case BC_LEX_KW_WHILE: { bc_parse_while(p); break; } case BC_LEX_EOF: case BC_LEX_INVALID: case BC_LEX_NEG: #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_TRUNC: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_POWER: case BC_LEX_OP_MULTIPLY: case BC_LEX_OP_DIVIDE: case BC_LEX_OP_MODULUS: case BC_LEX_OP_PLUS: #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_PLACES: case BC_LEX_OP_LSHIFT: case BC_LEX_OP_RSHIFT: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_REL_EQ: case BC_LEX_OP_REL_LE: case BC_LEX_OP_REL_GE: case BC_LEX_OP_REL_NE: case BC_LEX_OP_REL_LT: case BC_LEX_OP_REL_GT: case BC_LEX_OP_BOOL_OR: case BC_LEX_OP_BOOL_AND: case BC_LEX_OP_ASSIGN_POWER: case BC_LEX_OP_ASSIGN_MULTIPLY: case BC_LEX_OP_ASSIGN_DIVIDE: case BC_LEX_OP_ASSIGN_MODULUS: case BC_LEX_OP_ASSIGN_PLUS: case BC_LEX_OP_ASSIGN_MINUS: #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_ASSIGN_PLACES: case BC_LEX_OP_ASSIGN_LSHIFT: case BC_LEX_OP_ASSIGN_RSHIFT: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_ASSIGN: case BC_LEX_NLINE: case BC_LEX_WHITESPACE: case BC_LEX_RPAREN: case BC_LEX_LBRACKET: case BC_LEX_COMMA: case BC_LEX_RBRACKET: case BC_LEX_LBRACE: case BC_LEX_KW_AUTO: case BC_LEX_KW_DEFINE: #if DC_ENABLED case BC_LEX_EXTENDED_REGISTERS: case BC_LEX_EQ_NO_REG: case BC_LEX_COLON: case BC_LEX_EXECUTE: case BC_LEX_PRINT_STACK: case BC_LEX_CLEAR_STACK: case BC_LEX_REG_STACK_LEVEL: case BC_LEX_STACK_LEVEL: case BC_LEX_DUPLICATE: case BC_LEX_SWAP: case BC_LEX_POP: case BC_LEX_STORE_IBASE: case BC_LEX_STORE_OBASE: case BC_LEX_STORE_SCALE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_STORE_SEED: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_LOAD: case BC_LEX_LOAD_POP: case BC_LEX_STORE_PUSH: case BC_LEX_PRINT_POP: case BC_LEX_NQUIT: case BC_LEX_EXEC_STACK_LENGTH: case BC_LEX_SCALE_FACTOR: case BC_LEX_ARRAY_LENGTH: #endif // DC_ENABLED { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } } // If the flags did not change, we expect a delimiter. if (len == p->flags.len && flags == BC_PARSE_TOP_FLAG(p)) { if (BC_ERR(!bc_parse_isDelimiter(p))) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } } // Make sure semicolons are eaten. while (p->l.t == BC_LEX_SCOLON || p->l.t == BC_LEX_NLINE) { bc_lex_next(&p->l); } // POSIX's grammar does not allow a function definition after a semicolon // without a newline, so check specifically for that case and error if // the POSIX standard flag is set. if (p->l.last == BC_LEX_SCOLON && p->l.t == BC_LEX_KW_DEFINE && BC_IS_POSIX) { bc_parse_err(p, BC_ERR_POSIX_FUNC_AFTER_SEMICOLON); } } void bc_parse_parse(BcParse* p) { assert(p); BC_SETJMP_LOCKED(vm, exit); // We should not let an EOF get here unless some partial parse was not // completed, in which case, it's the user's fault. if (BC_ERR(p->l.t == BC_LEX_EOF)) bc_parse_err(p, BC_ERR_PARSE_EOF); // Functions need special parsing. else if (p->l.t == BC_LEX_KW_DEFINE) { if (BC_ERR(BC_PARSE_NO_EXEC(p))) { bc_parse_endif(p); if (BC_ERR(BC_PARSE_NO_EXEC(p))) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } } bc_parse_func(p); } // Otherwise, parse a normal statement. else bc_parse_stmt(p); exit: // We need to reset on error. if (BC_ERR(((vm->status && vm->status != BC_STATUS_QUIT) || vm->sig != 0))) { bc_parse_reset(p); } BC_LONGJMP_CONT(vm); BC_SIG_MAYLOCK; } /** * Parse an expression. This is the actual implementation of the Shunting-Yard * Algorithm. * @param p The parser. * @param flags The flags for what is valid in the expression. * @param next A set of tokens for what is valid *after* the expression. * @return A parse status. In some places, an empty expression is an * error, and sometimes, it is required. This allows this function * to tell the caller if the expression was empty and let the * caller handle it. */ static BcParseStatus bc_parse_expr_err(BcParse* p, uint8_t flags, BcParseNext next) { BcInst prev = BC_INST_PRINT; uchar inst = BC_INST_INVALID; BcLexType top, t; size_t nexprs, ops_bgn; uint32_t i, nparens, nrelops; bool pfirst, rprn, array_last, done, get_token, assign; bool bin_last, incdec, can_assign; // One of these *must* be true. assert(!(flags & BC_PARSE_PRINT) || !(flags & BC_PARSE_NEEDVAL)); // These are set very carefully. In fact, controlling the values of these // locals is the biggest part of making this work. ops_bgn especially is // important because it marks where the operator stack begins for *this* // invocation of this function. That's because bc_parse_expr_err() is // recursive (the Shunting-Yard Algorithm is most easily expressed // recursively when parsing subexpressions), and each invocation needs to // know where to stop. // // - nparens is the number of left parens without matches. // - nrelops is the number of relational operators that appear in the expr. // - nexprs is the number of unused expressions. // - rprn is a right paren encountered last. // - array_last is an array item encountered last. // - done means the expression has been fully parsed. // - get_token is true when a token is needed at the end of an iteration. // - assign is true when an assignment statement was parsed last. // - incdec is true when the previous operator was an inc or dec operator. // - can_assign is true when an assignemnt is valid. // - bin_last is true when the previous instruction was a binary operator. t = p->l.t; pfirst = (p->l.t == BC_LEX_LPAREN); nparens = nrelops = 0; nexprs = 0; ops_bgn = p->ops.len; rprn = array_last = done = get_token = assign = incdec = can_assign = false; bin_last = true; // We want to eat newlines if newlines are not a valid ending token. // This is for spacing in things like for loop headers. if (!(flags & BC_PARSE_NOREAD)) { while ((t = p->l.t) == BC_LEX_NLINE) { bc_lex_next(&p->l); } } // This is the Shunting-Yard algorithm loop. for (; !done && BC_PARSE_EXPR(t); t = p->l.t) { // Make sure an array expression is not mixed with any others. However, // a right parenthesis may end the expression, so we will need to take // care of that right there. if (BC_ERR(array_last && t != BC_LEX_RPAREN)) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } switch (t) { case BC_LEX_OP_INC: case BC_LEX_OP_DEC: { // These operators can only be used with items that can be // assigned to. if (BC_ERR(incdec)) bc_parse_err(p, BC_ERR_PARSE_ASSIGN); bc_parse_incdec(p, &prev, &can_assign, &nexprs, flags); rprn = get_token = bin_last = false; incdec = true; flags &= ~(BC_PARSE_ARRAY); break; } #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_TRUNC: { // The previous token must have been a leaf expression, or the // operator is in the wrong place. if (BC_ERR(!BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_TOKEN); } // I can just add the instruction because // negative will already be taken care of. bc_parse_push(p, BC_INST_TRUNC); rprn = can_assign = incdec = false; get_token = true; flags &= ~(BC_PARSE_ARRAY); break; } #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_MINUS: { bc_parse_minus(p, &prev, ops_bgn, rprn, bin_last, &nexprs); rprn = get_token = can_assign = false; // This is true if it was a binary operator last. bin_last = (prev == BC_INST_MINUS); if (bin_last) incdec = false; flags &= ~(BC_PARSE_ARRAY); break; } // All of this group, including the fallthrough, is to parse binary // operators. case BC_LEX_OP_ASSIGN_POWER: case BC_LEX_OP_ASSIGN_MULTIPLY: case BC_LEX_OP_ASSIGN_DIVIDE: case BC_LEX_OP_ASSIGN_MODULUS: case BC_LEX_OP_ASSIGN_PLUS: case BC_LEX_OP_ASSIGN_MINUS: #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_ASSIGN_PLACES: case BC_LEX_OP_ASSIGN_LSHIFT: case BC_LEX_OP_ASSIGN_RSHIFT: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_ASSIGN: { // We need to make sure the assignment is valid. if (!BC_PARSE_INST_VAR(prev)) { bc_parse_err(p, BC_ERR_PARSE_ASSIGN); } // Fallthrough. BC_FALLTHROUGH } case BC_LEX_OP_POWER: case BC_LEX_OP_MULTIPLY: case BC_LEX_OP_DIVIDE: case BC_LEX_OP_MODULUS: case BC_LEX_OP_PLUS: #if BC_ENABLE_EXTRA_MATH case BC_LEX_OP_PLACES: case BC_LEX_OP_LSHIFT: case BC_LEX_OP_RSHIFT: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_OP_REL_EQ: case BC_LEX_OP_REL_LE: case BC_LEX_OP_REL_GE: case BC_LEX_OP_REL_NE: case BC_LEX_OP_REL_LT: case BC_LEX_OP_REL_GT: case BC_LEX_OP_BOOL_NOT: case BC_LEX_OP_BOOL_OR: case BC_LEX_OP_BOOL_AND: { // This is true if the operator if the token is a prefix // operator. This is only for boolean not. if (BC_PARSE_OP_PREFIX(t)) { // Prefix operators are only allowed after binary operators // or prefix operators. if (BC_ERR(!bin_last && !BC_PARSE_OP_PREFIX(p->l.last))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } } // If we execute the else, that means we have a binary operator. // If the previous operator was a prefix or a binary operator, // then a binary operator is not allowed. else if (BC_ERR(BC_PARSE_PREV_PREFIX(prev) || bin_last)) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } nrelops += (t >= BC_LEX_OP_REL_EQ && t <= BC_LEX_OP_REL_GT); prev = BC_PARSE_TOKEN_INST(t); bc_parse_operator(p, t, ops_bgn, &nexprs); rprn = incdec = can_assign = false; get_token = true; bin_last = !BC_PARSE_OP_PREFIX(t); flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_LPAREN: { // A left paren is *not* allowed right after a leaf expr. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } nparens += 1; rprn = incdec = can_assign = false; get_token = true; // Push the paren onto the operator stack. bc_vec_push(&p->ops, &t); break; } case BC_LEX_RPAREN: { // This needs to be a status. The error is handled in // bc_parse_expr_status(). if (BC_ERR(p->l.last == BC_LEX_LPAREN)) { return BC_PARSE_STATUS_EMPTY_EXPR; } // The right paren must not come after a prefix or binary // operator. if (BC_ERR(bin_last || BC_PARSE_PREV_PREFIX(prev))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } // If there are no parens left, we are done, but we need another // token. if (!nparens) { done = true; get_token = false; break; } // Now that we know the right paren has not ended the // expression, make sure an array expression is not mixed with // any others. if (BC_ERR(array_last)) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } nparens -= 1; rprn = true; get_token = bin_last = incdec = false; bc_parse_rightParen(p, &nexprs); break; } case BC_LEX_STR: { // POSIX only allows strings alone. if (BC_IS_POSIX) bc_parse_err(p, BC_ERR_POSIX_EXPR_STRING); // A string is a leaf and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } bc_parse_addString(p); get_token = true; bin_last = rprn = false; nexprs += 1; break; } case BC_LEX_NAME: { // A name is a leaf and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } get_token = bin_last = false; bc_parse_name(p, &prev, &can_assign, flags & ~BC_PARSE_NOCALL); rprn = (prev == BC_INST_CALL); array_last = (prev == BC_INST_ARRAY); nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_NUMBER: { // A number is a leaf and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } // The number instruction is pushed in here. bc_parse_number(p); nexprs += 1; prev = BC_INST_NUM; get_token = true; rprn = bin_last = can_assign = false; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_KW_IBASE: case BC_LEX_KW_LAST: case BC_LEX_KW_OBASE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_SEED: #endif // BC_ENABLE_EXTRA_MATH { // All of these are leaves and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } prev = t - BC_LEX_KW_LAST + BC_INST_LAST; bc_parse_push(p, prev); get_token = can_assign = true; rprn = bin_last = false; nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_KW_LENGTH: case BC_LEX_KW_SQRT: case BC_LEX_KW_ABS: case BC_LEX_KW_IS_NUMBER: case BC_LEX_KW_IS_STRING: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_IRAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_ASCIIFY: { // All of these are leaves and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } bc_parse_builtin(p, t, flags, &prev); rprn = get_token = bin_last = incdec = can_assign = false; nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_KW_READ: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_RAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_MAXIBASE: case BC_LEX_KW_MAXOBASE: case BC_LEX_KW_MAXSCALE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_KW_MAXRAND: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_KW_LINE_LENGTH: case BC_LEX_KW_GLOBAL_STACKS: case BC_LEX_KW_LEADING_ZERO: { // All of these are leaves and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } // Error if we have read and it's not allowed. else if (t == BC_LEX_KW_READ && BC_ERR(flags & BC_PARSE_NOREAD)) { bc_parse_err(p, BC_ERR_EXEC_REC_READ); } prev = t - BC_LEX_KW_READ + BC_INST_READ; bc_parse_noArgBuiltin(p, prev); rprn = get_token = bin_last = incdec = can_assign = false; nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_KW_SCALE: { // This is a leaf and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } // Scale needs special work because it can be a variable *or* a // function. bc_parse_scale(p, &prev, &can_assign, flags); rprn = get_token = bin_last = false; nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_KW_MODEXP: case BC_LEX_KW_DIVMOD: { // This is a leaf and cannot come right after a leaf. if (BC_ERR(BC_PARSE_LEAF(prev, bin_last, rprn))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } bc_parse_builtin3(p, t, flags, &prev); rprn = get_token = bin_last = incdec = can_assign = false; nexprs += 1; flags &= ~(BC_PARSE_ARRAY); break; } case BC_LEX_EOF: case BC_LEX_INVALID: case BC_LEX_NEG: case BC_LEX_NLINE: case BC_LEX_WHITESPACE: case BC_LEX_LBRACKET: case BC_LEX_COMMA: case BC_LEX_RBRACKET: case BC_LEX_LBRACE: case BC_LEX_SCOLON: case BC_LEX_RBRACE: case BC_LEX_KW_AUTO: case BC_LEX_KW_BREAK: case BC_LEX_KW_CONTINUE: case BC_LEX_KW_DEFINE: case BC_LEX_KW_FOR: case BC_LEX_KW_IF: case BC_LEX_KW_LIMITS: case BC_LEX_KW_RETURN: case BC_LEX_KW_WHILE: case BC_LEX_KW_HALT: case BC_LEX_KW_PRINT: case BC_LEX_KW_QUIT: case BC_LEX_KW_STREAM: case BC_LEX_KW_ELSE: #if DC_ENABLED case BC_LEX_EXTENDED_REGISTERS: case BC_LEX_EQ_NO_REG: case BC_LEX_COLON: case BC_LEX_EXECUTE: case BC_LEX_PRINT_STACK: case BC_LEX_CLEAR_STACK: case BC_LEX_REG_STACK_LEVEL: case BC_LEX_STACK_LEVEL: case BC_LEX_DUPLICATE: case BC_LEX_SWAP: case BC_LEX_POP: case BC_LEX_STORE_IBASE: case BC_LEX_STORE_OBASE: case BC_LEX_STORE_SCALE: #if BC_ENABLE_EXTRA_MATH case BC_LEX_STORE_SEED: #endif // BC_ENABLE_EXTRA_MATH case BC_LEX_LOAD: case BC_LEX_LOAD_POP: case BC_LEX_STORE_PUSH: case BC_LEX_PRINT_POP: case BC_LEX_NQUIT: case BC_LEX_EXEC_STACK_LENGTH: case BC_LEX_SCALE_FACTOR: case BC_LEX_ARRAY_LENGTH: #endif // DC_ENABLED { #if BC_DEBUG // We should never get here, even in debug builds. bc_parse_err(p, BC_ERR_PARSE_TOKEN); break; #endif // BC_DEBUG } } if (get_token) bc_lex_next(&p->l); } // Now that we have parsed the expression, we need to empty the operator // stack. while (p->ops.len > ops_bgn) { top = BC_PARSE_TOP_OP(p); assign = top >= BC_LEX_OP_ASSIGN_POWER && top <= BC_LEX_OP_ASSIGN; // There should not be *any* parens on the stack anymore. if (BC_ERR(top == BC_LEX_LPAREN || top == BC_LEX_RPAREN)) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } bc_parse_push(p, BC_PARSE_TOKEN_INST(top)); // Adjust the number of unused expressions. nexprs -= !BC_PARSE_OP_PREFIX(top); bc_vec_pop(&p->ops); incdec = false; } // There must be only one expression at the top. if (BC_ERR(nexprs != 1)) bc_parse_err(p, BC_ERR_PARSE_EXPR); // Check that the next token is correct. for (i = 0; i < next.len && t != next.tokens[i]; ++i) { continue; } if (BC_ERR(i == next.len && !bc_parse_isDelimiter(p))) { bc_parse_err(p, BC_ERR_PARSE_EXPR); } // Check that POSIX would be happy with the number of relational operators. if (!(flags & BC_PARSE_REL) && nrelops) { bc_parse_err(p, BC_ERR_POSIX_REL_POS); } else if ((flags & BC_PARSE_REL) && nrelops > 1) { bc_parse_err(p, BC_ERR_POSIX_MULTIREL); } // If this is true, then we might be in a situation where we don't print. // We would want to have the increment/decrement operator not make an extra // copy if it's not necessary. if (!(flags & BC_PARSE_NEEDVAL) && !pfirst) { // We have the easy case if the last operator was an assignment // operator. if (assign) { inst = *((uchar*) bc_vec_top(&p->func->code)); inst += (BC_INST_ASSIGN_POWER_NO_VAL - BC_INST_ASSIGN_POWER); incdec = false; } // If we have an inc/dec operator and we are *not* printing, implement // the optimization to get rid of the extra copy. else if (incdec && !(flags & BC_PARSE_PRINT)) { inst = *((uchar*) bc_vec_top(&p->func->code)); incdec = (inst <= BC_INST_DEC); inst = BC_INST_ASSIGN_PLUS_NO_VAL + (inst != BC_INST_INC && inst != BC_INST_ASSIGN_PLUS); } // This condition allows us to change the previous assignment // instruction (which does a copy) for a NO_VAL version, which does not. // This condition is set if either of the above if statements ends up // being true. if (inst >= BC_INST_ASSIGN_POWER_NO_VAL && inst <= BC_INST_ASSIGN_NO_VAL) { // Pop the previous assignment instruction and push a new one. // Inc/dec needs the extra instruction because it is now a binary // operator and needs a second operand. bc_vec_pop(&p->func->code); if (incdec) bc_parse_push(p, BC_INST_ONE); bc_parse_push(p, inst); } } // If we might have to print... if ((flags & BC_PARSE_PRINT)) { // With a paren first or the last operator not being an assignment, we // *do* want to print. if (pfirst || !assign) bc_parse_push(p, BC_INST_PRINT); } // We need to make sure to push a pop instruction for assignment statements // that will not print. The print will pop, but without it, we need to pop. else if (!(flags & BC_PARSE_NEEDVAL) && (inst < BC_INST_ASSIGN_POWER_NO_VAL || inst > BC_INST_ASSIGN_NO_VAL)) { bc_parse_push(p, BC_INST_POP); } // We want to eat newlines if newlines are not a valid ending token. // This is for spacing in things like for loop headers. // // Yes, this is one case where I reuse a variable for a different purpose; // in this case, incdec being true now means that newlines are not valid. for (incdec = true, i = 0; i < next.len && incdec; ++i) { incdec = (next.tokens[i] != BC_LEX_NLINE); } if (incdec) { while (p->l.t == BC_LEX_NLINE) { bc_lex_next(&p->l); } } return BC_PARSE_STATUS_SUCCESS; } /** * Parses an expression with bc_parse_expr_err(), but throws an error if it gets * an empty expression. * @param p The parser. * @param flags The flags for what is valid in the expression. * @param next A set of tokens for what is valid *after* the expression. */ static void bc_parse_expr_status(BcParse* p, uint8_t flags, BcParseNext next) { BcParseStatus s = bc_parse_expr_err(p, flags, next); if (BC_ERR(s == BC_PARSE_STATUS_EMPTY_EXPR)) { bc_parse_err(p, BC_ERR_PARSE_EMPTY_EXPR); } } void bc_parse_expr(BcParse* p, uint8_t flags) { assert(p); bc_parse_expr_status(p, flags, bc_parse_next_read); } #endif // BC_ENABLED