1 /* 2 * Copyright (c) 1980 Regents of the University of California. 3 * Copyright (c) 1976 Board of Trustees of the University of Illinois. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms are permitted 7 * provided that the above copyright notice and this paragraph are 8 * duplicated in all such forms and that any documentation, 9 * advertising materials, and other materials related to such 10 * distribution and use acknowledge that the software was developed 11 * by the University of California, Berkeley and the University 12 * of Illinois, Urbana. The name of either 13 * University may not be used to endorse or promote products derived 14 * from this software without specific prior written permission. 15 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 17 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 18 */ 19 20 #ifndef lint 21 static char sccsid[] = "@(#)parse.c 5.6 (Berkeley) 06/29/88"; 22 #endif /* not lint */ 23 24 /* 25 * FILE NAME: 26 * parse.c 27 * 28 * PURPOSE: 29 * Contains the routines which keep track of the parse stack. 30 * 31 * GLOBALS: 32 * ps.p_stack = The parse stack, set by both routines 33 * ps.il = Stack of indentation levels, set by parse 34 * ps.cstk = Stack of case statement indentation levels, set by parse 35 * ps.tos = Pointer to top of stack, set by both routines. 36 * 37 * FUNCTIONS: 38 * parse 39 * reduce 40 */ 41 /*- 42 * Copyright (C) 1976 by the Board of Trustees of the University of Illinois 43 * 44 * All rights reserved 45 * 46 * 47 * NAME: parse 48 * 49 * FUNCTION: Parse is given one input which is a "maxi token" just scanned 50 * from input. Maxi tokens are signifigant constructs such as else, {, 51 * do, if (...), etc. Parse works with reduce to maintain a parse stack 52 * of these constructs. Parse is responsible for the "shift" portion of 53 * the parse algorithm, and reduce handles the "reduce" portion. 54 * 55 * HISTORY: initial coding November 1976 D A Willcox of CAC 56 * 57 */ 58 59 #include "./indent_globs.h" 60 #include "./indent_codes.h" 61 62 63 64 65 parse(tk) 66 int tk; /* the code for the construct scanned */ 67 { 68 int i; 69 70 #ifdef debug 71 printf("%2d - %s\n", tk, token); 72 #endif 73 while (ps.p_stack[ps.tos] == ifhead && tk != elselit) { 74 /* true if we have an if without an else */ 75 ps.p_stack[ps.tos] = stmt; /* apply the if(..) stmt ::= stmt 76 * reduction */ 77 reduce(); /* see if this allows any reduction */ 78 } 79 80 81 switch (tk) { /* go on and figure out what to do with 82 * the input */ 83 84 case decl: /* scanned a declaration word */ 85 ps.search_brace = btype_2; 86 /* indicate that following brace should be on same line */ 87 if (ps.p_stack[ps.tos] != decl) { /* only put one declaration onto 88 * stack */ 89 break_comma = true; /* while in declaration, newline 90 * should be forced after comma */ 91 ps.p_stack[++ps.tos] = decl; 92 ps.il[ps.tos] = ps.i_l_follow; 93 94 if (ps.ljust_decl) { /* only do if we want left 95 * justified declarations */ 96 ps.ind_level = 0; 97 for (i = ps.tos - 1; i > 0; --i) 98 if (ps.p_stack[i] == decl) 99 ++ps.ind_level; /* indentation is number 100 * of declaration levels 101 * deep we are */ 102 ps.i_l_follow = ps.ind_level; 103 } 104 } 105 break; 106 107 case ifstmt: /* scanned if (...) */ 108 if (ps.p_stack[ps.tos] == elsehead && ps.else_if) /* "else if ..." */ 109 ps.i_l_follow = ps.il[ps.tos]; 110 case dolit: /* 'do' */ 111 case forstmt: /* for (...) */ 112 ps.p_stack[++ps.tos] = tk; 113 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 114 ++ps.i_l_follow; /* subsequent statements should be 115 * indented 1 */ 116 ps.search_brace = btype_2; 117 break; 118 119 case lbrace: /* scanned { */ 120 break_comma = false;/* don't break comma in an initial list */ 121 if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl 122 || ps.p_stack[ps.tos] == stmtl) 123 ++ps.i_l_follow; /* it is a random, isolated stmt group or 124 * a declaration */ 125 else { 126 if (s_code == e_code) { 127 /* only do this if there is nothing on the line */ 128 --ps.ind_level; 129 /* it is a group as part of a while, for, etc. */ 130 if (ps.p_stack[ps.tos] == swstmt && ps.case_indent) 131 --ps.ind_level; 132 /* 133 * for a switch, brace should be two levels out from 134 * the code 135 */ 136 } 137 } 138 139 ps.p_stack[++ps.tos] = lbrace; 140 ps.il[ps.tos] = ps.ind_level; 141 ps.p_stack[++ps.tos] = stmt; 142 /* allow null stmt between braces */ 143 ps.il[ps.tos] = ps.i_l_follow; 144 break; 145 146 case whilestmt: /* scanned while (...) */ 147 if (ps.p_stack[ps.tos] == dohead) { 148 /* it is matched with do stmt */ 149 ps.ind_level = ps.i_l_follow = ps.il[ps.tos]; 150 ps.p_stack[++ps.tos] = whilestmt; 151 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 152 } 153 else { /* it is a while loop */ 154 ps.p_stack[++ps.tos] = whilestmt; 155 ps.il[ps.tos] = ps.i_l_follow; 156 ++ps.i_l_follow; 157 ps.search_brace = btype_2; 158 } 159 160 break; 161 162 case elselit: /* scanned an else */ 163 164 if (ps.p_stack[ps.tos] != ifhead) 165 diag(1,"Unmatched 'else'"); 166 else { 167 ps.ind_level = ps.il[ps.tos]; /* indentation for else should be same as for if */ 168 ps.i_l_follow = ps.ind_level + 1; /* everything following should be in 1 level */ 169 ps.p_stack[ps.tos] = elsehead; 170 /* remember if with else */ 171 ps.search_brace = btype_2; 172 } 173 174 break; 175 176 case rbrace: /* scanned a } */ 177 /* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */ 178 if (ps.p_stack[ps.tos - 1] == lbrace) { 179 ps.ind_level = ps.i_l_follow = ps.il[--ps.tos]; 180 ps.p_stack[ps.tos] = stmt; 181 } 182 else 183 diag(1,"Stmt nesting error."); 184 break; 185 186 case swstmt: /* had switch (...) */ 187 ps.p_stack[++ps.tos] = swstmt; 188 ps.cstk[ps.tos] = case_ind; 189 /* save current case indent level */ 190 ps.il[ps.tos] = ps.i_l_follow; 191 case_ind = ps.i_l_follow + ps.case_indent; /* cases should be one 192 * level down from 193 * switch */ 194 ps.i_l_follow += ps.case_indent + 1; /* statements should be 195 * two levels in */ 196 ps.search_brace = btype_2; 197 break; 198 199 case semicolon: /* this indicates a simple stmt */ 200 break_comma = false;/* turn off flag to break after commas in 201 * a declaration */ 202 ps.p_stack[++ps.tos] = stmt; 203 ps.il[ps.tos] = ps.ind_level; 204 break; 205 206 default: /* this is an error */ 207 diag(1,"Unknown code to parser"); 208 return; 209 210 211 } /* end of switch */ 212 213 reduce(); /* see if any reduction can be done */ 214 #ifdef debug 215 for (i = 1; i <= ps.tos; ++i) 216 printf("(%d %d)", ps.p_stack[i], ps.il[i]); 217 printf("\n"); 218 #endif 219 return; 220 } 221 /* 222 * Copyright (C) 1976 by the Board of Trustees of the University of Illinois 223 * 224 * All rights reserved 225 * 226 * 227 * NAME: reduce 228 * 229 * FUNCTION: Implements the reduce part of the parsing algorithm 230 * 231 * ALGORITHM: The following reductions are done. Reductions are repeated 232 * until no more are possible. 233 * 234 * Old TOS New TOS <stmt> <stmt> <stmtl> <stmtl> <stmt> <stmtl> do 235 * <stmt> "dostmt" if <stmt> "ifstmt" switch <stmt> <stmt> 236 * decl <stmt> <stmt> "ifelse" <stmt> <stmt> for <stmt> <stmt> 237 * while <stmt> <stmt> "dostmt" while <stmt> 238 * 239 * On each reduction, ps.i_l_follow (the indentation for the following line) is 240 * set to the indentation level associated with the old TOS. 241 * 242 * PARAMETERS: None 243 * 244 * RETURNS: Nothing 245 * 246 * GLOBALS: ps.cstk ps.i_l_follow = ps.il ps.p_stack = ps.tos = 247 * 248 * CALLS: None 249 * 250 * CALLED BY: parse 251 * 252 * HISTORY: initial coding November 1976 D A Willcox of CAC 253 * 254 */ 255 /*----------------------------------------------*\ 256 * | REDUCTION PHASE 257 \*----------------------------------------------*/ 258 reduce() { 259 260 register int i; 261 262 for (;;) { /* keep looping until there is nothing 263 * left to reduce */ 264 265 switch (ps.p_stack[ps.tos]) { 266 267 case stmt: 268 switch (ps.p_stack[ps.tos - 1]) { 269 270 case stmt: 271 case stmtl: 272 /* stmtl stmt or stmt stmt */ 273 ps.p_stack[--ps.tos] = stmtl; 274 break; 275 276 case dolit: /* <do> <stmt> */ 277 ps.p_stack[--ps.tos] = dohead; 278 ps.i_l_follow = ps.il[ps.tos]; 279 break; 280 281 case ifstmt: 282 /* <if> <stmt> */ 283 ps.p_stack[--ps.tos] = ifhead; 284 for (i = ps.tos - 1; 285 ( 286 ps.p_stack[i] != stmt 287 && 288 ps.p_stack[i] != stmtl 289 && 290 ps.p_stack[i] != lbrace 291 ); 292 --i); 293 ps.i_l_follow = ps.il[i]; 294 /* 295 * for the time being, we will assume that there 296 * is no else on this if, and set the indentation 297 * level accordingly. If an else is scanned, it 298 * will be fixed up later 299 */ 300 break; 301 302 case swstmt: 303 /* <switch> <stmt> */ 304 case_ind = ps.cstk[ps.tos - 1]; 305 306 case decl: /* finish of a declaration */ 307 case elsehead: 308 /* <<if> <stmt> else> <stmt> */ 309 case forstmt: 310 /* <for> <stmt> */ 311 case whilestmt: 312 /* <while> <stmt> */ 313 ps.p_stack[--ps.tos] = stmt; 314 ps.i_l_follow = ps.il[ps.tos]; 315 break; 316 317 default: /* <anything else> <stmt> */ 318 return; 319 320 } /* end of section for <stmt> on top of 321 * stack */ 322 break; 323 324 case whilestmt: /* while (...) on top */ 325 if (ps.p_stack[ps.tos - 1] == dohead) { 326 /* it is termination of a do while */ 327 ps.p_stack[--ps.tos] = stmt; 328 break; 329 } 330 else 331 return; 332 333 default: /* anything else on top */ 334 return; 335 336 } 337 } 338 } 339