1 /* $NetBSD: parse.c,v 1.18 2021/03/12 23:10:18 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 #if 0 41 #ifndef lint 42 static char sccsid[] = "@(#)parse.c 8.1 (Berkeley) 6/6/93"; 43 #endif /* not lint */ 44 #endif 45 46 #include <sys/cdefs.h> 47 #ifndef lint 48 #if defined(__NetBSD__) 49 __RCSID("$FreeBSD$"); 50 #else 51 __FBSDID("$FreeBSD: head/usr.bin/indent/parse.c 337651 2018-08-11 19:20:06Z pstef $"); 52 #endif 53 #endif 54 55 #include <err.h> 56 #include <stdio.h> 57 58 #include "indent.h" 59 60 static void reduce(void); 61 62 void 63 parse(token_type tk) /* tk: the code for the construct scanned */ 64 { 65 int i; 66 67 #ifdef debug 68 printf("parse token: '%s' \"%s\"\n", token_type_name(tk), token); 69 #endif 70 71 while (ps.p_stack[ps.tos] == if_expr_stmt && tk != keyword_else) { 72 /* true if we have an if without an else */ 73 ps.p_stack[ps.tos] = stmt; /* apply the if(..) stmt ::= stmt 74 * reduction */ 75 reduce(); /* see if this allows any reduction */ 76 } 77 78 79 switch (tk) { /* go on and figure out what to do with the 80 * input */ 81 82 case decl: /* scanned a declaration word */ 83 ps.search_brace = opt.btype_2; 84 /* indicate that following brace should be on same line */ 85 if (ps.p_stack[ps.tos] != decl) { /* only put one declaration 86 * onto stack */ 87 break_comma = true; /* while in declaration, newline should be 88 * forced after comma */ 89 ps.p_stack[++ps.tos] = decl; 90 ps.il[ps.tos] = ps.i_l_follow; 91 92 if (opt.ljust_decl) {/* only do if we want left justified 93 * declarations */ 94 ps.ind_level = 0; 95 for (i = ps.tos - 1; i > 0; --i) 96 if (ps.p_stack[i] == decl) 97 ++ps.ind_level; /* indentation is number of 98 * declaration levels deep we are */ 99 ps.i_l_follow = ps.ind_level; 100 } 101 } 102 break; 103 104 case if_expr: /* 'if' '(' <expr> ')' */ 105 if (ps.p_stack[ps.tos] == if_expr_stmt_else && opt.else_if) { 106 /* 107 * Note that the stack pointer here is decremented, effectively 108 * reducing "else if" to "if". This saves a lot of stack space 109 * in case of a long "if-else-if ... else-if" sequence. 110 */ 111 ps.i_l_follow = ps.il[ps.tos--]; 112 } 113 /* the rest is the same as for keyword_do and for_exprs */ 114 /* FALLTHROUGH */ 115 case keyword_do: /* 'do' */ 116 case for_exprs: /* 'for' (...) */ 117 ps.p_stack[++ps.tos] = tk; 118 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 119 ++ps.i_l_follow; /* subsequent statements should be indented 1 */ 120 ps.search_brace = opt.btype_2; 121 break; 122 123 case lbrace: /* scanned { */ 124 break_comma = false; /* don't break comma in an initial list */ 125 if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl 126 || ps.p_stack[ps.tos] == stmt_list) 127 ++ps.i_l_follow; /* it is a random, isolated stmt group or a 128 * declaration */ 129 else { 130 if (s_code == e_code) { 131 /* 132 * only do this if there is nothing on the line 133 */ 134 --ps.ind_level; 135 /* 136 * it is a group as part of a while, for, etc. 137 */ 138 if (ps.p_stack[ps.tos] == switch_expr && opt.case_indent >= 1) 139 --ps.ind_level; 140 /* 141 * for a switch, brace should be two levels out from the code 142 */ 143 } 144 } 145 146 ps.p_stack[++ps.tos] = lbrace; 147 ps.il[ps.tos] = ps.ind_level; 148 ps.p_stack[++ps.tos] = stmt; 149 /* allow null stmt between braces */ 150 ps.il[ps.tos] = ps.i_l_follow; 151 break; 152 153 case while_expr: /* 'while' '(' <expr> ')' */ 154 if (ps.p_stack[ps.tos] == do_stmt) { 155 /* it is matched with do stmt */ 156 ps.ind_level = ps.i_l_follow = ps.il[ps.tos]; 157 ps.p_stack[++ps.tos] = while_expr; 158 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 159 } else { /* it is a while loop */ 160 ps.p_stack[++ps.tos] = while_expr; 161 ps.il[ps.tos] = ps.i_l_follow; 162 ++ps.i_l_follow; 163 ps.search_brace = opt.btype_2; 164 } 165 166 break; 167 168 case keyword_else: 169 if (ps.p_stack[ps.tos] != if_expr_stmt) 170 diag(1, "Unmatched 'else'"); 171 else { 172 ps.ind_level = ps.il[ps.tos]; /* indentation for else should 173 * be same as for if */ 174 ps.i_l_follow = ps.ind_level + 1; /* everything following should 175 * be in 1 level */ 176 ps.p_stack[ps.tos] = if_expr_stmt_else; 177 /* remember if with else */ 178 ps.search_brace = opt.btype_2 | opt.else_if; 179 } 180 break; 181 182 case rbrace: /* scanned a } */ 183 /* stack should have <lbrace> <stmt> or <lbrace> <stmt_list> */ 184 if (ps.tos > 0 && ps.p_stack[ps.tos - 1] == lbrace) { 185 ps.ind_level = ps.i_l_follow = ps.il[--ps.tos]; 186 ps.p_stack[ps.tos] = stmt; 187 } else 188 diag(1, "Statement nesting error"); 189 break; 190 191 case switch_expr: /* had switch (...) */ 192 ps.p_stack[++ps.tos] = switch_expr; 193 ps.cstk[ps.tos] = case_ind; 194 /* save current case indent level */ 195 ps.il[ps.tos] = ps.i_l_follow; 196 case_ind = ps.i_l_follow + opt.case_indent; /* cases should be one 197 * level down from 198 * switch */ 199 ps.i_l_follow += opt.case_indent + 1; /* statements should be two 200 * levels in */ 201 ps.search_brace = opt.btype_2; 202 break; 203 204 case semicolon: /* this indicates a simple stmt */ 205 break_comma = false; /* turn off flag to break after commas in a 206 * declaration */ 207 ps.p_stack[++ps.tos] = stmt; 208 ps.il[ps.tos] = ps.ind_level; 209 break; 210 211 default: /* this is an error */ 212 diag(1, "Unknown code to parser"); 213 return; 214 215 216 } /* end of switch */ 217 218 if (ps.tos >= STACKSIZE - 1) 219 errx(1, "Parser stack overflow"); 220 221 reduce(); /* see if any reduction can be done */ 222 223 #ifdef debug 224 printf("parse stack:"); 225 for (i = 1; i <= ps.tos; ++i) 226 printf(" ('%s' at %d)", token_type_name(ps.p_stack[i]), ps.il[i]); 227 if (ps.tos == 0) 228 printf(" empty"); 229 printf("\n"); 230 #endif 231 } 232 233 /*----------------------------------------------*\ 234 | REDUCTION PHASE | 235 \*----------------------------------------------*/ 236 237 /* 238 * Try to combine the statement on the top of the parse stack with the symbol 239 * directly below it, replacing these two symbols with a single symbol. 240 */ 241 static int 242 reduce_stmt(void) 243 { 244 switch (ps.p_stack[ps.tos - 1]) { 245 246 case stmt: /* stmt stmt */ 247 case stmt_list: /* stmt_list stmt */ 248 ps.p_stack[--ps.tos] = stmt_list; 249 return true; 250 251 case keyword_do: /* 'do' <stmt> */ 252 ps.p_stack[--ps.tos] = do_stmt; 253 ps.i_l_follow = ps.il[ps.tos]; 254 return true; 255 256 case if_expr: /* 'if' '(' <expr> ')' <stmt> */ 257 ps.p_stack[--ps.tos] = if_expr_stmt; 258 int i = ps.tos - 1; 259 while (ps.p_stack[i] != stmt && 260 ps.p_stack[i] != stmt_list && 261 ps.p_stack[i] != lbrace) 262 --i; 263 ps.i_l_follow = ps.il[i]; 264 /* 265 * for the time being, we will assume that there is no else on 266 * this if, and set the indentation level accordingly. If an 267 * else is scanned, it will be fixed up later 268 */ 269 return true; 270 271 case switch_expr: /* 'switch' '(' <expr> ')' <stmt> */ 272 case_ind = ps.cstk[ps.tos - 1]; 273 /* FALLTHROUGH */ 274 case decl: /* finish of a declaration */ 275 case if_expr_stmt_else: /* 'if' '(' <expr> ')' <stmt> 'else' <stmt> */ 276 case for_exprs: /* 'for' '(' ... ')' <stmt> */ 277 case while_expr: /* 'while' '(' <expr> ')' <stmt> */ 278 ps.p_stack[--ps.tos] = stmt; 279 ps.i_l_follow = ps.il[ps.tos]; 280 return true; 281 282 default: /* <anything else> <stmt> */ 283 return false; 284 } 285 } 286 287 /* 288 * Repeatedly try to reduce the top two symbols on the parse stack to a 289 * single symbol, until no more reductions are possible. 290 * 291 * On each reduction, ps.i_l_follow (the indentation for the following line) 292 * is set to the indentation level associated with the old TOS. 293 */ 294 static void 295 reduce(void) 296 { 297 again: 298 if (ps.p_stack[ps.tos] == stmt) { 299 if (reduce_stmt()) 300 goto again; 301 } else if (ps.p_stack[ps.tos] == while_expr) { 302 if (ps.p_stack[ps.tos - 1] == do_stmt) { 303 ps.tos -= 2; 304 goto again; 305 } 306 } 307 } 308