parse.c revision 1.68
1 /* $NetBSD: parse.c,v 1.68 2023/06/06 05:11:11 rillig Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-4-Clause 5 * 6 * Copyright (c) 1985 Sun Microsystems, Inc. 7 * Copyright (c) 1980, 1993 8 * The Regents of the University of California. All rights reserved. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #include <sys/cdefs.h> 41 __RCSID("$NetBSD: parse.c,v 1.68 2023/06/06 05:11:11 rillig Exp $"); 42 43 #include <err.h> 44 45 #include "indent.h" 46 47 /* 48 * Try to combine the statement on the top of the parse stack with the symbol 49 * directly below it, replacing these two symbols with a single symbol. 50 */ 51 static bool 52 reduce_stmt(void) 53 { 54 switch (ps.s_sym[ps.tos - 1]) { 55 56 case psym_stmt: 57 case psym_stmt_list: 58 ps.s_sym[--ps.tos] = psym_stmt_list; 59 return true; 60 61 case psym_do: 62 ps.s_sym[--ps.tos] = psym_do_stmt; 63 ps.ind_level_follow = ps.s_ind_level[ps.tos]; 64 return true; 65 66 case psym_if_expr: 67 ps.s_sym[--ps.tos] = psym_if_expr_stmt; 68 int i = ps.tos - 1; 69 while (ps.s_sym[i] != psym_stmt && 70 ps.s_sym[i] != psym_stmt_list && 71 ps.s_sym[i] != psym_lbrace_block) 72 --i; 73 ps.ind_level_follow = ps.s_ind_level[i]; 74 /* For the time being, assume that there is no 'else' on this 75 * 'if', and set the indentation level accordingly. If an 76 * 'else' is scanned, it will be fixed up later. */ 77 return true; 78 79 case psym_switch_expr: 80 case psym_decl: 81 case psym_if_expr_stmt_else: 82 case psym_for_exprs: 83 case psym_while_expr: 84 ps.s_sym[--ps.tos] = psym_stmt; 85 ps.ind_level_follow = ps.s_ind_level[ps.tos]; 86 return true; 87 88 default: 89 return false; 90 } 91 } 92 93 static int 94 decl_level(void) 95 { 96 int level = 0; 97 for (int i = ps.tos - 1; i > 0; i--) 98 if (ps.s_sym[i] == psym_decl) 99 level++; 100 return level; 101 } 102 103 static void 104 ps_push(parser_symbol psym) 105 { 106 ps.s_sym[++ps.tos] = psym; 107 ps.s_ind_level[ps.tos] = ps.ind_level; 108 } 109 110 static void 111 ps_push_follow(parser_symbol psym) 112 { 113 ps.s_sym[++ps.tos] = psym; 114 ps.s_ind_level[ps.tos] = ps.ind_level_follow; 115 } 116 117 /* 118 * Repeatedly try to reduce the top two symbols on the parse stack to a single 119 * symbol, until no more reductions are possible. 120 */ 121 static void 122 reduce(void) 123 { 124 again: 125 if (ps.s_sym[ps.tos] == psym_stmt && reduce_stmt()) 126 goto again; 127 if (ps.s_sym[ps.tos] == psym_while_expr && 128 ps.s_sym[ps.tos - 1] == psym_do_stmt) { 129 ps.tos -= 2; 130 goto again; 131 } 132 } 133 134 static bool 135 is_lbrace(parser_symbol psym) 136 { 137 return psym == psym_lbrace_block 138 || psym == psym_lbrace_struct 139 || psym == psym_lbrace_union 140 || psym == psym_lbrace_enum; 141 } 142 143 /* 144 * Shift the token onto the parser stack, or reduce it by combining it with 145 * previous tokens. 146 */ 147 void 148 parse(parser_symbol psym) 149 { 150 debug_blank_line(); 151 debug_println("parse token: %s", psym_name[psym]); 152 153 if (psym != psym_else) { 154 while (ps.s_sym[ps.tos] == psym_if_expr_stmt) { 155 ps.s_sym[ps.tos] = psym_stmt; 156 reduce(); 157 } 158 } 159 160 switch (psym) { 161 162 case psym_decl: 163 if (ps.s_sym[ps.tos] == psym_decl) 164 break; /* only put one declaration onto stack */ 165 166 ps.break_after_comma = true; 167 ps_push_follow(psym_decl); 168 169 if (opt.left_justify_decl) 170 ps.ind_level_follow = ps.ind_level = decl_level(); 171 break; 172 173 case psym_if_expr: 174 if (ps.s_sym[ps.tos] == psym_if_expr_stmt_else 175 && opt.else_if_in_same_line) 176 ps.ind_level_follow = ps.s_ind_level[ps.tos--]; 177 /* FALLTHROUGH */ 178 case psym_do: 179 case psym_for_exprs: 180 ps.ind_level = ps.ind_level_follow++; 181 ps_push(psym); 182 break; 183 184 case psym_lbrace_block: 185 case psym_lbrace_struct: 186 case psym_lbrace_union: 187 case psym_lbrace_enum: 188 ps.break_after_comma = false; 189 if (ps.s_sym[ps.tos] == psym_stmt 190 || ps.s_sym[ps.tos] == psym_decl 191 || ps.s_sym[ps.tos] == psym_stmt_list) 192 ++ps.ind_level_follow; /* it is a random, isolated 193 * stmt group or a declaration 194 */ 195 else { 196 if (code.len == 0) { 197 /* it is a group as part of a while, for, etc. 198 */ 199 --ps.ind_level; 200 201 /* for a switch, brace should be two levels out 202 * from the code */ 203 if (ps.s_sym[ps.tos] == psym_switch_expr && 204 opt.case_indent >= 1.0F) 205 --ps.ind_level; 206 } 207 } 208 209 ps_push(psym); 210 ps_push_follow(psym_stmt); 211 break; 212 213 case psym_while_expr: 214 if (ps.s_sym[ps.tos] == psym_do_stmt) { 215 ps.ind_level = 216 ps.ind_level_follow = ps.s_ind_level[ps.tos]; 217 ps_push(psym_while_expr); 218 } else { 219 ps_push_follow(psym_while_expr); 220 ++ps.ind_level_follow; 221 } 222 223 break; 224 225 case psym_else: 226 if (ps.s_sym[ps.tos] != psym_if_expr_stmt) { 227 diag(1, "Unmatched 'else'"); 228 break; 229 } 230 ps.ind_level = ps.s_ind_level[ps.tos]; 231 ps.ind_level_follow = ps.ind_level + 1; 232 ps.s_sym[ps.tos] = psym_if_expr_stmt_else; 233 break; 234 235 case psym_rbrace: 236 /* stack should have <lbrace> <stmt> or <lbrace> <stmt_list> */ 237 if (!(ps.tos > 0 && is_lbrace(ps.s_sym[ps.tos - 1]))) { 238 diag(1, "Statement nesting error"); 239 break; 240 } 241 ps.ind_level = ps.ind_level_follow = ps.s_ind_level[--ps.tos]; 242 ps.s_sym[ps.tos] = psym_stmt; 243 break; 244 245 case psym_switch_expr: 246 ps_push_follow(psym_switch_expr); 247 ps.ind_level_follow += (int)opt.case_indent + 1; 248 break; 249 250 case psym_stmt: 251 ps.break_after_comma = false; 252 ps_push(psym_stmt); 253 break; 254 255 default: 256 diag(1, "Unknown code to parser"); 257 return; 258 } 259 260 if (ps.tos >= STACKSIZE - 1) 261 errx(1, "Parser stack overflow"); 262 263 debug_parse_stack("before reduction"); 264 reduce(); /* see if any reduction can be done */ 265 debug_parse_stack("after reduction"); 266 } 267
Indexes created Mon Sep 22 21:09:42 GMT 2025