usr.bin/indent/parse.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1985 Sun Microsystems, Inc.
   5  * Copyright (c) 1980, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)parse.c  8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: head/usr.bin/indent/parse.c 337651 2018-08-11 19:20:06Z pstef $
  35  */
  36
  37 #include <err.h>
  38 #include <stdio.h>
  39 #include "indent_globs.h"
  40 #include "indent_codes.h"
  41 #include "indent.h"
  42
  43 static void reduce(void);
  44
  45 void
  46 parse(int tk) /* tk: the code for the construct scanned */
  47 {
  48     int         i;
  49
  50 #ifdef debug
  51     printf("%2d - %s\n", tk, token);
  52 #endif
  53
  54     while (ps.p_stack[ps.tos] == ifhead && tk != elselit) {
  55         /* true if we have an if without an else */
  56         ps.p_stack[ps.tos] = stmt;      /* apply the if(..) stmt ::= stmt
  57                                          * reduction */
  58         reduce();               /* see if this allows any reduction */
  59     }
  60
  61
  62     switch (tk) {               /* go on and figure out what to do with the
  63                                  * input */
  64
  65     case decl:                  /* scanned a declaration word */
  66         ps.search_brace = opt.btype_2;
  67         /* indicate that following brace should be on same line */
  68         if (ps.p_stack[ps.tos] != decl) {       /* only put one declaration
  69                                                  * onto stack */
  70             break_comma = true; /* while in declaration, newline should be
  71                                  * forced after comma */
  72             ps.p_stack[++ps.tos] = decl;
  73             ps.il[ps.tos] = ps.i_l_follow;
  74
  75             if (opt.ljust_decl) {/* only do if we want left justified
  76                                  * declarations */
  77                 ps.ind_level = 0;
  78                 for (i = ps.tos - 1; i > 0; --i)
  79                     if (ps.p_stack[i] == decl)
  80                         ++ps.ind_level; /* indentation is number of
  81                                          * declaration levels deep we are */
  82                 ps.i_l_follow = ps.ind_level;
  83             }
  84         }
  85         break;
  86
  87     case ifstmt:                /* scanned if (...) */
  88         if (ps.p_stack[ps.tos] == elsehead && opt.else_if) /* "else if ..." */
  89                 /*
  90                  * Note that the stack pointer here is decremented, effectively
  91                  * reducing "else if" to "if". This saves a lot of stack space
  92                  * in case of a long "if-else-if ... else-if" sequence.
  93                  */
  94                 ps.i_l_follow = ps.il[ps.tos--];
  95         /* the rest is the same as for dolit and forstmt */
  96         /* FALLTHROUGH */
  97     case dolit:         /* 'do' */
  98     case forstmt:               /* for (...) */
  99         ps.p_stack[++ps.tos] = tk;
 100         ps.il[ps.tos] = ps.ind_level = ps.i_l_follow;
 101         ++ps.i_l_follow;        /* subsequent statements should be indented 1 */
 102         ps.search_brace = opt.btype_2;
 103         break;
 104
 105     case lbrace:                /* scanned { */
 106         break_comma = false;    /* don't break comma in an initial list */
 107         if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl
 108                 || ps.p_stack[ps.tos] == stmtl)
 109             ++ps.i_l_follow;    /* it is a random, isolated stmt group or a
 110                                  * declaration */
 111         else {
 112             if (s_code == e_code) {
 113                 /*
 114                  * only do this if there is nothing on the line
 115                  */
 116                 --ps.ind_level;
 117                 /*
 118                  * it is a group as part of a while, for, etc.
 119                  */
 120                 if (ps.p_stack[ps.tos] == swstmt && opt.case_indent >= 1)
 121                     --ps.ind_level;
 122                 /*
 123                  * for a switch, brace should be two levels out from the code
 124                  */
 125             }
 126         }
 127
 128         ps.p_stack[++ps.tos] = lbrace;
 129         ps.il[ps.tos] = ps.ind_level;
 130         ps.p_stack[++ps.tos] = stmt;
 131         /* allow null stmt between braces */
 132         ps.il[ps.tos] = ps.i_l_follow;
 133         break;
 134
 135     case whilestmt:             /* scanned while (...) */
 136         if (ps.p_stack[ps.tos] == dohead) {
 137             /* it is matched with do stmt */
 138             ps.ind_level = ps.i_l_follow = ps.il[ps.tos];
 139             ps.p_stack[++ps.tos] = whilestmt;
 140             ps.il[ps.tos] = ps.ind_level = ps.i_l_follow;
 141         }
 142         else {                  /* it is a while loop */
 143             ps.p_stack[++ps.tos] = whilestmt;
 144             ps.il[ps.tos] = ps.i_l_follow;
 145             ++ps.i_l_follow;
 146             ps.search_brace = opt.btype_2;
 147         }
 148
 149         break;
 150
 151     case elselit:               /* scanned an else */
 152
 153         if (ps.p_stack[ps.tos] != ifhead)
 154             diag2(1, "Unmatched 'else'");
 155         else {
 156             ps.ind_level = ps.il[ps.tos];       /* indentation for else should
 157                                                  * be same as for if */
 158             ps.i_l_follow = ps.ind_level + 1;   /* everything following should
 159                                                  * be in 1 level */
 160             ps.p_stack[ps.tos] = elsehead;
 161             /* remember if with else */
 162             ps.search_brace = opt.btype_2 | opt.else_if;
 163         }
 164         break;
 165
 166     case rbrace:                /* scanned a } */
 167         /* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */
 168         if (ps.tos > 0 && ps.p_stack[ps.tos - 1] == lbrace) {
 169             ps.ind_level = ps.i_l_follow = ps.il[--ps.tos];
 170             ps.p_stack[ps.tos] = stmt;
 171         }
 172         else
 173             diag2(1, "Statement nesting error");
 174         break;
 175
 176     case swstmt:                /* had switch (...) */
 177         ps.p_stack[++ps.tos] = swstmt;
 178         ps.cstk[ps.tos] = case_ind;
 179         /* save current case indent level */
 180         ps.il[ps.tos] = ps.i_l_follow;
 181         case_ind = ps.i_l_follow + opt.case_indent;     /* cases should be one
 182                                                          * level down from
 183                                                          * switch */
 184         ps.i_l_follow += opt.case_indent + 1;   /* statements should be two
 185                                                  * levels in */
 186         ps.search_brace = opt.btype_2;
 187         break;
 188
 189     case semicolon:             /* this indicates a simple stmt */
 190         break_comma = false;    /* turn off flag to break after commas in a
 191                                  * declaration */
 192         ps.p_stack[++ps.tos] = stmt;
 193         ps.il[ps.tos] = ps.ind_level;
 194         break;
 195
 196     default:                    /* this is an error */
 197         diag2(1, "Unknown code to parser");
 198         return;
 199
 200
 201     }                           /* end of switch */
 202
 203     if (ps.tos >= STACKSIZE - 1)
 204         errx(1, "Parser stack overflow");
 205
 206     reduce();                   /* see if any reduction can be done */
 207
 208 #ifdef debug
 209     for (i = 1; i <= ps.tos; ++i)
 210         printf("(%d %d)", ps.p_stack[i], ps.il[i]);
 211     printf("\n");
 212 #endif
 213
 214     return;
 215 }
 216
 217 /*
 218  * NAME: reduce
 219  *
 220  * FUNCTION: Implements the reduce part of the parsing algorithm
 221  *
 222  * ALGORITHM: The following reductions are done.  Reductions are repeated
 223  *      until no more are possible.
 224  *
 225  * Old TOS              New TOS
 226  * <stmt> <stmt>        <stmtl>
 227  * <stmtl> <stmt>       <stmtl>
 228  * do <stmt>            "dostmt"
 229  * if <stmt>            "ifstmt"
 230  * switch <stmt>        <stmt>
 231  * decl <stmt>          <stmt>
 232  * "ifelse" <stmt>      <stmt>
 233  * for <stmt>           <stmt>
 234  * while <stmt>         <stmt>
 235  * "dostmt" while       <stmt>
 236  *
 237  * On each reduction, ps.i_l_follow (the indentation for the following line)
 238  * is set to the indentation level associated with the old TOS.
 239  *
 240  * PARAMETERS: None
 241  *
 242  * RETURNS: Nothing
 243  *
 244  * GLOBALS: ps.cstk ps.i_l_follow = ps.il ps.p_stack = ps.tos =
 245  *
 246  * CALLS: None
 247  *
 248  * CALLED BY: parse
 249  *
 250  * HISTORY: initial coding      November 1976   D A Willcox of CAC
 251  *
 252  */
 253 /*----------------------------------------------*\
 254 |   REDUCTION PHASE                                 |
 255 \*----------------------------------------------*/
 256 static void
 257 reduce(void)
 258 {
 259     int i;
 260
 261     for (;;) {                  /* keep looping until there is nothing left to
 262                                  * reduce */
 263
 264         switch (ps.p_stack[ps.tos]) {
 265
 266         case stmt:
 267             switch (ps.p_stack[ps.tos - 1]) {
 268
 269             case stmt:
 270             case stmtl:
 271                 /* stmtl stmt or stmt stmt */
 272                 ps.p_stack[--ps.tos] = stmtl;
 273                 break;
 274
 275             case dolit: /* <do> <stmt> */
 276                 ps.p_stack[--ps.tos] = dohead;
 277                 ps.i_l_follow = ps.il[ps.tos];
 278                 break;
 279
 280             case ifstmt:
 281                 /* <if> <stmt> */
 282                 ps.p_stack[--ps.tos] = ifhead;
 283                 for (i = ps.tos - 1;
 284                         (
 285                          ps.p_stack[i] != stmt
 286                          &&
 287                          ps.p_stack[i] != stmtl
 288                          &&
 289                          ps.p_stack[i] != lbrace
 290                          );
 291                         --i);
 292                 ps.i_l_follow = ps.il[i];
 293                 /*
 294                  * for the time being, we will assume that there is no else on
 295                  * this if, and set the indentation level accordingly. If an
 296                  * else is scanned, it will be fixed up later
 297                  */
 298                 break;
 299
 300             case swstmt:
 301                 /* <switch> <stmt> */
 302                 case_ind = ps.cstk[ps.tos - 1];
 303                 /* FALLTHROUGH */
 304             case decl:          /* finish of a declaration */
 305             case elsehead:
 306                 /* <<if> <stmt> else> <stmt> */
 307             case forstmt:
 308                 /* <for> <stmt> */
 309             case whilestmt:
 310                 /* <while> <stmt> */
 311                 ps.p_stack[--ps.tos] = stmt;
 312                 ps.i_l_follow = ps.il[ps.tos];
 313                 break;
 314
 315             default:            /* <anything else> <stmt> */
 316                 return;
 317
 318             }                   /* end of section for <stmt> on top of stack */
 319             break;
 320
 321         case whilestmt: /* while (...) on top */
 322             if (ps.p_stack[ps.tos - 1] == dohead) {
 323                 /* it is termination of a do while */
 324                 ps.tos -= 2;
 325                 break;
 326             }
 327             else
 328                 return;
 329
 330         default:                /* anything else on top */
 331             return;
 332
 333         }
 334     }
 335 }