2 * *****************************************************************************
4 * SPDX-License-Identifier: BSD-2-Clause
6 * Copyright (c) 2018-2021 Gavin D. Howard and contributors.
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30 * *****************************************************************************
32 * Definitions for bc's parser.
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
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
56 #define BC_PARSE_REL (UINTMAX_C(1)<<0)
58 /// A flag that requires that the expression is valid for a print statement.
59 #define BC_PARSE_PRINT (UINTMAX_C(1)<<1)
61 /// A flag that requires that the expression does *not* have any function call.
62 #define BC_PARSE_NOCALL (UINTMAX_C(1)<<2)
64 /// A flag that requires that the expression does *not* have a read() expression.
65 #define BC_PARSE_NOREAD (UINTMAX_C(1)<<3)
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)
71 /// A flag that requires that the expression is not empty and returns a value.
72 #define BC_PARSE_NEEDVAL (UINTMAX_C(1)<<5)
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.
80 #define BC_PARSE_IS_INITED(p, prg) ((p)->prog == (prg))
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.
89 #define BC_PARSE_CAN_PARSE(p) \
90 ((p).l.t != BC_LEX_EOF && (p).l.t != BC_LEX_KW_DEFINE)
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.
99 #define BC_PARSE_CAN_PARSE(p) ((p).l.t != BC_LEX_EOF)
104 * Pushes the instruction @a i onto the bytecode vector for the current
106 * @param p The parser.
107 * @param i The instruction to push onto the bytecode vector.
109 #define bc_parse_push(p, i) (bc_vec_pushByte(&(p)->func->code, (uchar) (i)))
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
115 * @param p The parser.
116 * @param idx The index to push onto the bytecode vector.
118 #define bc_parse_pushIndex(p, idx) (bc_vec_pushIndex(&(p)->func->code, (idx)))
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.
126 #define bc_parse_err(p, e) (bc_vm_handleError((e), (p)->l.line))
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.
135 #define bc_parse_verr(p, e, ...) \
136 (bc_vm_handleError((e), (p)->l.line, __VA_ARGS__))
138 // Forward declarations.
143 * A function pointer to call when more parsing is needed.
144 * @param p The parser.
146 typedef void (*BcParseParse)(struct BcParse* p);
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.)
154 typedef void (*BcParseExpr)(struct BcParse* p, uint8_t flags);
156 /// The parser struct.
157 typedef struct BcParse {
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.
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.
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.
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).
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.
193 /// A reference to the program to grab the current function when necessary.
194 struct BcProgram *prog;
196 /// A reference to the current function. The function is what holds the
197 /// bytecode vector that the parser is filling.
200 /// The index of the function.
204 /// True if the bc parser just entered a function and an auto statement
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.
217 void bc_parse_init(BcParse *p, struct BcProgram *prog, size_t func);
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.
224 void bc_parse_free(BcParse *p);
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.
231 void bc_parse_reset(BcParse *p);
234 * Adds a string. See @a BcProgram in include/program.h for more details.
235 * @param p The parser that parsed the string.
237 void bc_parse_addString(BcParse *p);
240 * Adds a number. See @a BcProgram in include/program.h for more details.
241 * @param p The parser that parsed the number.
243 void bc_parse_number(BcParse *p);
246 * Update the current function in the parser.
247 * @param p The parser.
248 * @param fidx The index of the new function.
250 void bc_parse_updateFunc(BcParse *p, size_t fidx);
253 * Adds a new variable or array. See @a BcProgram in include/program.h for more
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.
259 void bc_parse_pushName(const BcParse* p, char *name, bool var);
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.
267 void bc_parse_text(BcParse *p, const char *text, bool is_stdin);
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];