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 this notice is preserved and that due credit is given 8 * to the University of California at Berkeley and the University of 9 * Illinois at Urbana. The name of either University may not be used 10 * to endorse or promote products derived from this software without 11 * specific prior written permission. This software is provided 12 * ``as is'' without express or implied warranty. 13 */ 14 15 #ifndef lint 16 static char sccsid[] = "@(#)parse.c 5.5 (Berkeley) 03/22/88"; 17 #endif /* not lint */ 18 19 /* 20 * FILE NAME: 21 * parse.c 22 * 23 * PURPOSE: 24 * Contains the routines which keep track of the parse stack. 25 * 26 * GLOBALS: 27 * ps.p_stack = The parse stack, set by both routines 28 * ps.il = Stack of indentation levels, set by parse 29 * ps.cstk = Stack of case statement indentation levels, set by parse 30 * ps.tos = Pointer to top of stack, set by both routines. 31 * 32 * FUNCTIONS: 33 * parse 34 * reduce 35 */ 36 /*- 37 * Copyright (C) 1976 by the Board of Trustees of the University of Illinois 38 * 39 * All rights reserved 40 * 41 * 42 * NAME: parse 43 * 44 * FUNCTION: Parse is given one input which is a "maxi token" just scanned 45 * from input. Maxi tokens are signifigant constructs such as else, {, 46 * do, if (...), etc. Parse works with reduce to maintain a parse stack 47 * of these constructs. Parse is responsible for the "shift" portion of 48 * the parse algorithm, and reduce handles the "reduce" portion. 49 * 50 * HISTORY: initial coding November 1976 D A Willcox of CAC 51 * 52 */ 53 54 #include "./indent_globs.h" 55 #include "./indent_codes.h" 56 57 58 59 60 parse(tk) 61 int tk; /* the code for the construct scanned */ 62 { 63 int i; 64 65 #ifdef debug 66 printf("%2d - %s\n", tk, token); 67 #endif 68 while (ps.p_stack[ps.tos] == ifhead && tk != elselit) { 69 /* true if we have an if without an else */ 70 ps.p_stack[ps.tos] = stmt; /* apply the if(..) stmt ::= stmt 71 * reduction */ 72 reduce(); /* see if this allows any reduction */ 73 } 74 75 76 switch (tk) { /* go on and figure out what to do with 77 * the input */ 78 79 case decl: /* scanned a declaration word */ 80 ps.search_brace = btype_2; 81 /* indicate that following brace should be on same line */ 82 if (ps.p_stack[ps.tos] != decl) { /* only put one declaration onto 83 * stack */ 84 break_comma = true; /* while in declaration, newline 85 * should be forced after comma */ 86 ps.p_stack[++ps.tos] = decl; 87 ps.il[ps.tos] = ps.i_l_follow; 88 89 if (ps.ljust_decl) { /* only do if we want left 90 * justified declarations */ 91 ps.ind_level = 0; 92 for (i = ps.tos - 1; i > 0; --i) 93 if (ps.p_stack[i] == decl) 94 ++ps.ind_level; /* indentation is number 95 * of declaration levels 96 * deep we are */ 97 ps.i_l_follow = ps.ind_level; 98 } 99 } 100 break; 101 102 case ifstmt: /* scanned if (...) */ 103 if (ps.p_stack[ps.tos] == elsehead && ps.else_if) /* "else if ..." */ 104 ps.i_l_follow = ps.il[ps.tos]; 105 case dolit: /* 'do' */ 106 case forstmt: /* for (...) */ 107 ps.p_stack[++ps.tos] = tk; 108 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 109 ++ps.i_l_follow; /* subsequent statements should be 110 * indented 1 */ 111 ps.search_brace = btype_2; 112 break; 113 114 case lbrace: /* scanned { */ 115 break_comma = false;/* don't break comma in an initial list */ 116 if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl 117 || ps.p_stack[ps.tos] == stmtl) 118 ++ps.i_l_follow; /* it is a random, isolated stmt group or 119 * a declaration */ 120 else { 121 if (s_code == e_code) { 122 /* only do this if there is nothing on the line */ 123 --ps.ind_level; 124 /* it is a group as part of a while, for, etc. */ 125 if (ps.p_stack[ps.tos] == swstmt && ps.case_indent) 126 --ps.ind_level; 127 /* 128 * for a switch, brace should be two levels out from 129 * the code 130 */ 131 } 132 } 133 134 ps.p_stack[++ps.tos] = lbrace; 135 ps.il[ps.tos] = ps.ind_level; 136 ps.p_stack[++ps.tos] = stmt; 137 /* allow null stmt between braces */ 138 ps.il[ps.tos] = ps.i_l_follow; 139 break; 140 141 case whilestmt: /* scanned while (...) */ 142 if (ps.p_stack[ps.tos] == dohead) { 143 /* it is matched with do stmt */ 144 ps.ind_level = ps.i_l_follow = ps.il[ps.tos]; 145 ps.p_stack[++ps.tos] = whilestmt; 146 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 147 } 148 else { /* it is a while loop */ 149 ps.p_stack[++ps.tos] = whilestmt; 150 ps.il[ps.tos] = ps.i_l_follow; 151 ++ps.i_l_follow; 152 ps.search_brace = btype_2; 153 } 154 155 break; 156 157 case elselit: /* scanned an else */ 158 159 if (ps.p_stack[ps.tos] != ifhead) 160 diag(1,"Unmatched 'else'"); 161 else { 162 ps.ind_level = ps.il[ps.tos]; /* indentation for else should be same as for if */ 163 ps.i_l_follow = ps.ind_level + 1; /* everything following should be in 1 level */ 164 ps.p_stack[ps.tos] = elsehead; 165 /* remember if with else */ 166 ps.search_brace = btype_2; 167 } 168 169 break; 170 171 case rbrace: /* scanned a } */ 172 /* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */ 173 if (ps.p_stack[ps.tos - 1] == lbrace) { 174 ps.ind_level = ps.i_l_follow = ps.il[--ps.tos]; 175 ps.p_stack[ps.tos] = stmt; 176 } 177 else 178 diag(1,"Stmt nesting error."); 179 break; 180 181 case swstmt: /* had switch (...) */ 182 ps.p_stack[++ps.tos] = swstmt; 183 ps.cstk[ps.tos] = case_ind; 184 /* save current case indent level */ 185 ps.il[ps.tos] = ps.i_l_follow; 186 case_ind = ps.i_l_follow + ps.case_indent; /* cases should be one 187 * level down from 188 * switch */ 189 ps.i_l_follow += ps.case_indent + 1; /* statements should be 190 * two levels in */ 191 ps.search_brace = btype_2; 192 break; 193 194 case semicolon: /* this indicates a simple stmt */ 195 break_comma = false;/* turn off flag to break after commas in 196 * a declaration */ 197 ps.p_stack[++ps.tos] = stmt; 198 ps.il[ps.tos] = ps.ind_level; 199 break; 200 201 default: /* this is an error */ 202 diag(1,"Unknown code to parser"); 203 return; 204 205 206 } /* end of switch */ 207 208 reduce(); /* see if any reduction can be done */ 209 #ifdef debug 210 for (i = 1; i <= ps.tos; ++i) 211 printf("(%d %d)", ps.p_stack[i], ps.il[i]); 212 printf("\n"); 213 #endif 214 return; 215 } 216 /* 217 * Copyright (C) 1976 by the Board of Trustees of the University of Illinois 218 * 219 * All rights reserved 220 * 221 * 222 * NAME: reduce 223 * 224 * FUNCTION: Implements the reduce part of the parsing algorithm 225 * 226 * ALGORITHM: The following reductions are done. Reductions are repeated 227 * until no more are possible. 228 * 229 * Old TOS New TOS <stmt> <stmt> <stmtl> <stmtl> <stmt> <stmtl> do 230 * <stmt> "dostmt" if <stmt> "ifstmt" switch <stmt> <stmt> 231 * decl <stmt> <stmt> "ifelse" <stmt> <stmt> for <stmt> <stmt> 232 * while <stmt> <stmt> "dostmt" while <stmt> 233 * 234 * On each reduction, ps.i_l_follow (the indentation for the following line) is 235 * set to the indentation level associated with the old TOS. 236 * 237 * PARAMETERS: None 238 * 239 * RETURNS: Nothing 240 * 241 * GLOBALS: ps.cstk ps.i_l_follow = ps.il ps.p_stack = ps.tos = 242 * 243 * CALLS: None 244 * 245 * CALLED BY: parse 246 * 247 * HISTORY: initial coding November 1976 D A Willcox of CAC 248 * 249 */ 250 /*----------------------------------------------*\ 251 * | REDUCTION PHASE 252 \*----------------------------------------------*/ 253 reduce() { 254 255 register int i; 256 257 for (;;) { /* keep looping until there is nothing 258 * left to reduce */ 259 260 switch (ps.p_stack[ps.tos]) { 261 262 case stmt: 263 switch (ps.p_stack[ps.tos - 1]) { 264 265 case stmt: 266 case stmtl: 267 /* stmtl stmt or stmt stmt */ 268 ps.p_stack[--ps.tos] = stmtl; 269 break; 270 271 case dolit: /* <do> <stmt> */ 272 ps.p_stack[--ps.tos] = dohead; 273 ps.i_l_follow = ps.il[ps.tos]; 274 break; 275 276 case ifstmt: 277 /* <if> <stmt> */ 278 ps.p_stack[--ps.tos] = ifhead; 279 for (i = ps.tos - 1; 280 ( 281 ps.p_stack[i] != stmt 282 && 283 ps.p_stack[i] != stmtl 284 && 285 ps.p_stack[i] != lbrace 286 ); 287 --i); 288 ps.i_l_follow = ps.il[i]; 289 /* 290 * for the time being, we will assume that there 291 * is no else on this if, and set the indentation 292 * level accordingly. If an else is scanned, it 293 * will be fixed up later 294 */ 295 break; 296 297 case swstmt: 298 /* <switch> <stmt> */ 299 case_ind = ps.cstk[ps.tos - 1]; 300 301 case decl: /* finish of a declaration */ 302 case elsehead: 303 /* <<if> <stmt> else> <stmt> */ 304 case forstmt: 305 /* <for> <stmt> */ 306 case whilestmt: 307 /* <while> <stmt> */ 308 ps.p_stack[--ps.tos] = stmt; 309 ps.i_l_follow = ps.il[ps.tos]; 310 break; 311 312 default: /* <anything else> <stmt> */ 313 return; 314 315 } /* end of section for <stmt> on top of 316 * stack */ 317 break; 318 319 case whilestmt: /* while (...) on top */ 320 if (ps.p_stack[ps.tos - 1] == dohead) { 321 /* it is termination of a do while */ 322 ps.p_stack[--ps.tos] = stmt; 323 break; 324 } 325 else 326 return; 327 328 default: /* anything else on top */ 329 return; 330 331 } 332 } 333 } 334