1 /* 2 * ***************************************************************************** 3 * 4 * SPDX-License-Identifier: BSD-2-Clause 5 * 6 * Copyright (c) 2018-2021 Gavin D. Howard and contributors. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions are met: 10 * 11 * * Redistributions of source code must retain the above copyright notice, this 12 * list of conditions and the following disclaimer. 13 * 14 * * Redistributions in binary form must reproduce the above copyright notice, 15 * this list of conditions and the following disclaimer in the documentation 16 * and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 * 30 * ***************************************************************************** 31 * 32 * Definitions for bc's parser. 33 * 34 */ 35 36 #ifndef BC_PARSE_H 37 #define BC_PARSE_H 38 39 #include <limits.h> 40 #include <stdbool.h> 41 #include <stdint.h> 42 43 #include <status.h> 44 #include <vector.h> 45 #include <lex.h> 46 #include <lang.h> 47 48 // The following are flags that can be passed to @a BcParseExpr functions. They 49 // define the requirements that the parsed expression must meet to not have an 50 // error thrown. 51 52 /// A flag that requires that the expression is valid for conditionals in for 53 /// loops, while loops, and if statements. This is because POSIX requires that 54 /// certain operators are *only* used in those cases. It's whacked, but that's 55 /// how it is. 56 #define BC_PARSE_REL (UINTMAX_C(1)<<0) 57 58 /// A flag that requires that the expression is valid for a print statement. 59 #define BC_PARSE_PRINT (UINTMAX_C(1)<<1) 60 61 /// A flag that requires that the expression does *not* have any function call. 62 #define BC_PARSE_NOCALL (UINTMAX_C(1)<<2) 63 64 /// A flag that requires that the expression does *not* have a read() expression. 65 #define BC_PARSE_NOREAD (UINTMAX_C(1)<<3) 66 67 /// A flag that *allows* (rather than requires) that an array appear in the 68 /// expression. This is mostly used as parameters in bc. 69 #define BC_PARSE_ARRAY (UINTMAX_C(1)<<4) 70 71 /// A flag that requires that the expression is not empty and returns a value. 72 #define BC_PARSE_NEEDVAL (UINTMAX_C(1)<<5) 73 74 /** 75 * Returns true if the parser has been initialized. 76 * @param p The parser. 77 * @param prg The program. 78 * @return True if @a p has been initialized, false otherwise. 79 */ 80 #define BC_PARSE_IS_INITED(p, prg) ((p)->prog == (prg)) 81 82 #if BC_ENABLED 83 84 /** 85 * Returns true if the current parser state allows parsing, false otherwise. 86 * @param p The parser. 87 * @return True if parsing can proceed, false otherwise. 88 */ 89 #define BC_PARSE_CAN_PARSE(p) \ 90 ((p).l.t != BC_LEX_EOF && (p).l.t != BC_LEX_KW_DEFINE) 91 92 #else // BC_ENABLED 93 94 /** 95 * Returns true if the current parser state allows parsing, false otherwise. 96 * @param p The parser. 97 * @return True if parsing can proceed, false otherwise. 98 */ 99 #define BC_PARSE_CAN_PARSE(p) ((p).l.t != BC_LEX_EOF) 100 101 #endif // BC_ENABLED 102 103 /** 104 * Pushes the instruction @a i onto the bytecode vector for the current 105 * function. 106 * @param p The parser. 107 * @param i The instruction to push onto the bytecode vector. 108 */ 109 #define bc_parse_push(p, i) (bc_vec_pushByte(&(p)->func->code, (uchar) (i))) 110 111 /** 112 * Pushes an index onto the bytecode vector. For more information, see 113 * @a bc_vec_pushIndex() in src/vector.c and @a bc_program_index() in 114 * src/program.c. 115 * @param p The parser. 116 * @param idx The index to push onto the bytecode vector. 117 */ 118 #define bc_parse_pushIndex(p, idx) (bc_vec_pushIndex(&(p)->func->code, (idx))) 119 120 /** 121 * A convenience macro for throwing errors in parse code. They take care of 122 * plumbing like passing in the current line the lexer is on. 123 * @param p The parser. 124 * @param e The error. 125 */ 126 #define bc_parse_err(p, e) (bc_vm_handleError((e), (p)->l.line)) 127 128 /** 129 * A convenience macro for throwing errors in parse code. They take care of 130 * plumbing like passing in the current line the lexer is on. 131 * @param p The parser. 132 * @param e The error. 133 * @param ... The varags that are needed. 134 */ 135 #define bc_parse_verr(p, e, ...) \ 136 (bc_vm_handleError((e), (p)->l.line, __VA_ARGS__)) 137 138 // Forward declarations. 139 struct BcParse; 140 struct BcProgram; 141 142 /** 143 * A function pointer to call when more parsing is needed. 144 * @param p The parser. 145 */ 146 typedef void (*BcParseParse)(struct BcParse* p); 147 148 /** 149 * A function pointer to call when an expression needs to be parsed. This can 150 * happen for read() expressions or dc strings. 151 * @param p The parser. 152 * @param flags The flags for what is allowed or required. (See flags above.) 153 */ 154 typedef void (*BcParseExpr)(struct BcParse* p, uint8_t flags); 155 156 /// The parser struct. 157 typedef struct BcParse { 158 159 /// The lexer. 160 BcLex l; 161 162 #if BC_ENABLED 163 /// The stack of flags for bc. (See comments in include/bc.h.) This stack is 164 /// *required* to have one item at all times. Not maintaining that invariant 165 /// will cause problems. 166 BcVec flags; 167 168 /// The stack of exits. These are indices into the bytecode vector where 169 /// blocks for loops and if statements end. Basically, these are the places 170 /// to jump to when skipping code. 171 BcVec exits; 172 173 /// The stack of conditionals. Unlike exits, which are indices to jump 174 /// *forward* to, this is a vector of indices to jump *backward* to, usually 175 /// to the conditional of a loop, hence the name. 176 BcVec conds; 177 178 /// A stack of operators. When parsing expressions, the bc parser uses the 179 /// Shunting-Yard algorithm, which requires a stack of operators. This can 180 /// hold the stack for multiple expressions at once because the expressions 181 /// stack as well. For more information, see the Expression Parsing section 182 /// of the Development manual (manuals/development.md). 183 BcVec ops; 184 185 /// A buffer to temporarily store a string in. This is because the lexer 186 /// might generate a string as part of its work, and the parser needs that 187 /// string, but it also needs the lexer to continue lexing, which might 188 /// overwrite the string stored in the lexer. This buffer is for copying 189 /// that string from the lexer to keep it safe. 190 BcVec buf; 191 #endif // BC_ENABLED 192 193 /// A reference to the program to grab the current function when necessary. 194 struct BcProgram *prog; 195 196 /// A reference to the current function. The function is what holds the 197 /// bytecode vector that the parser is filling. 198 BcFunc *func; 199 200 /// The index of the function. 201 size_t fidx; 202 203 #if BC_ENABLED 204 /// True if the bc parser just entered a function and an auto statement 205 /// would be valid. 206 bool auto_part; 207 #endif // BC_ENABLED 208 209 } BcParse; 210 211 /** 212 * Initializes a parser. 213 * @param p The parser to initialize. 214 * @param prog A referenc to the program. 215 * @param func The index of the current function. 216 */ 217 void bc_parse_init(BcParse *p, struct BcProgram *prog, size_t func); 218 219 /** 220 * Frees a parser. This is not guarded by #ifndef NDEBUG because a separate 221 * parser is created at runtime to parse read() expressions and dc strings. 222 * @param p The parser to free. 223 */ 224 void bc_parse_free(BcParse *p); 225 226 /** 227 * Resets the parser. Resetting means erasing all state to the point that the 228 * parser would think it was just initialized. 229 * @param p The parser to reset. 230 */ 231 void bc_parse_reset(BcParse *p); 232 233 /** 234 * Adds a string. See @a BcProgram in include/program.h for more details. 235 * @param p The parser that parsed the string. 236 */ 237 void bc_parse_addString(BcParse *p); 238 239 /** 240 * Adds a number. See @a BcProgram in include/program.h for more details. 241 * @param p The parser that parsed the number. 242 */ 243 void bc_parse_number(BcParse *p); 244 245 /** 246 * Update the current function in the parser. 247 * @param p The parser. 248 * @param fidx The index of the new function. 249 */ 250 void bc_parse_updateFunc(BcParse *p, size_t fidx); 251 252 /** 253 * Adds a new variable or array. See @a BcProgram in include/program.h for more 254 * details. 255 * @param p The parser that parsed the variable or array name. 256 * @param name The name of the variable or array to add. 257 * @param var True if the name is for a variable, false if it's for an array. 258 */ 259 void bc_parse_pushName(const BcParse* p, char *name, bool var); 260 261 /** 262 * Sets the text that the parser will parse. 263 * @param p The parser. 264 * @param text The text to lex. 265 * @param is_stdin True if the text is from stdin, false otherwise. 266 */ 267 void bc_parse_text(BcParse *p, const char *text, bool is_stdin); 268 269 // References to const 0 and 1 strings for special cases. bc and dc have 270 // specific instructions for 0 and 1 because they pop up so often and (in the 271 // case of 1), increment/decrement operators. 272 extern const char bc_parse_zero[2]; 273 extern const char bc_parse_one[2]; 274 275 #endif // BC_PARSE_H 276