1 /* 2 * Copyright (c) 1985 Sun Microsystems, Inc. 3 * Copyright (c) 1980 The Regents of the University of California. 4 * Copyright (c) 1976 Board of Trustees of the University of Illinois. 5 * All rights reserved. 6 * 7 * %sccs.include.redist.c% 8 */ 9 10 #ifndef lint 11 static char sccsid[] = "@(#)parse.c 5.11 (Berkeley) 06/01/90"; 12 #endif /* not lint */ 13 14 #include "indent_globs.h" 15 #include "indent_codes.h" 16 17 parse(tk) 18 int tk; /* the code for the construct scanned */ 19 { 20 int i; 21 22 #ifdef debug 23 printf("%2d - %s\n", tk, token); 24 #endif 25 26 while (ps.p_stack[ps.tos] == ifhead && tk != elselit) { 27 /* true if we have an if without an else */ 28 ps.p_stack[ps.tos] = stmt; /* apply the if(..) stmt ::= stmt 29 * reduction */ 30 reduce(); /* see if this allows any reduction */ 31 } 32 33 34 switch (tk) { /* go on and figure out what to do with the 35 * input */ 36 37 case decl: /* scanned a declaration word */ 38 ps.search_brace = btype_2; 39 /* indicate that following brace should be on same line */ 40 if (ps.p_stack[ps.tos] != decl) { /* only put one declaration 41 * onto stack */ 42 break_comma = true; /* while in declaration, newline should be 43 * forced after comma */ 44 ps.p_stack[++ps.tos] = decl; 45 ps.il[ps.tos] = ps.i_l_follow; 46 47 if (ps.ljust_decl) {/* only do if we want left justified 48 * declarations */ 49 ps.ind_level = 0; 50 for (i = ps.tos - 1; i > 0; --i) 51 if (ps.p_stack[i] == decl) 52 ++ps.ind_level; /* indentation is number of 53 * declaration levels deep we are */ 54 ps.i_l_follow = ps.ind_level; 55 } 56 } 57 break; 58 59 case ifstmt: /* scanned if (...) */ 60 if (ps.p_stack[ps.tos] == elsehead && ps.else_if) /* "else if ..." */ 61 ps.i_l_follow = ps.il[ps.tos]; 62 case dolit: /* 'do' */ 63 case forstmt: /* for (...) */ 64 ps.p_stack[++ps.tos] = tk; 65 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 66 ++ps.i_l_follow; /* subsequent statements should be indented 1 */ 67 ps.search_brace = btype_2; 68 break; 69 70 case lbrace: /* scanned { */ 71 break_comma = false; /* don't break comma in an initial list */ 72 if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl 73 || ps.p_stack[ps.tos] == stmtl) 74 ++ps.i_l_follow; /* it is a random, isolated stmt group or a 75 * declaration */ 76 else { 77 if (s_code == e_code) { 78 /* 79 * only do this if there is nothing on the line 80 */ 81 --ps.ind_level; 82 /* 83 * it is a group as part of a while, for, etc. 84 */ 85 if (ps.p_stack[ps.tos] == swstmt && ps.case_indent >= 1) 86 --ps.ind_level; 87 /* 88 * for a switch, brace should be two levels out from the code 89 */ 90 } 91 } 92 93 ps.p_stack[++ps.tos] = lbrace; 94 ps.il[ps.tos] = ps.ind_level; 95 ps.p_stack[++ps.tos] = stmt; 96 /* allow null stmt between braces */ 97 ps.il[ps.tos] = ps.i_l_follow; 98 break; 99 100 case whilestmt: /* scanned while (...) */ 101 if (ps.p_stack[ps.tos] == dohead) { 102 /* it is matched with do stmt */ 103 ps.ind_level = ps.i_l_follow = ps.il[ps.tos]; 104 ps.p_stack[++ps.tos] = whilestmt; 105 ps.il[ps.tos] = ps.ind_level = ps.i_l_follow; 106 } 107 else { /* it is a while loop */ 108 ps.p_stack[++ps.tos] = whilestmt; 109 ps.il[ps.tos] = ps.i_l_follow; 110 ++ps.i_l_follow; 111 ps.search_brace = btype_2; 112 } 113 114 break; 115 116 case elselit: /* scanned an else */ 117 118 if (ps.p_stack[ps.tos] != ifhead) 119 diag(1, "Unmatched 'else'"); 120 else { 121 ps.ind_level = ps.il[ps.tos]; /* indentation for else should 122 * be same as for if */ 123 ps.i_l_follow = ps.ind_level + 1; /* everything following should 124 * be in 1 level */ 125 ps.p_stack[ps.tos] = elsehead; 126 /* remember if with else */ 127 ps.search_brace = btype_2 | ps.else_if; 128 } 129 break; 130 131 case rbrace: /* scanned a } */ 132 /* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */ 133 if (ps.p_stack[ps.tos - 1] == lbrace) { 134 ps.ind_level = ps.i_l_follow = ps.il[--ps.tos]; 135 ps.p_stack[ps.tos] = stmt; 136 } 137 else 138 diag(1, "Stmt nesting error."); 139 break; 140 141 case swstmt: /* had switch (...) */ 142 ps.p_stack[++ps.tos] = swstmt; 143 ps.cstk[ps.tos] = case_ind; 144 /* save current case indent level */ 145 ps.il[ps.tos] = ps.i_l_follow; 146 case_ind = ps.i_l_follow + ps.case_indent; /* cases should be one 147 * level down from 148 * switch */ 149 ps.i_l_follow += ps.case_indent + 1; /* statements should be two 150 * levels in */ 151 ps.search_brace = btype_2; 152 break; 153 154 case semicolon: /* this indicates a simple stmt */ 155 break_comma = false; /* turn off flag to break after commas in a 156 * declaration */ 157 ps.p_stack[++ps.tos] = stmt; 158 ps.il[ps.tos] = ps.ind_level; 159 break; 160 161 default: /* this is an error */ 162 diag(1, "Unknown code to parser"); 163 return; 164 165 166 } /* end of switch */ 167 168 reduce(); /* see if any reduction can be done */ 169 170 #ifdef debug 171 for (i = 1; i <= ps.tos; ++i) 172 printf("(%d %d)", ps.p_stack[i], ps.il[i]); 173 printf("\n"); 174 #endif 175 176 return; 177 } 178 179 /* 180 * NAME: reduce 181 * 182 * FUNCTION: Implements the reduce part of the parsing algorithm 183 * 184 * ALGORITHM: The following reductions are done. Reductions are repeated 185 * until no more are possible. 186 * 187 * Old TOS New TOS 188 * <stmt> <stmt> <stmtl> 189 * <stmtl> <stmt> <stmtl> 190 * do <stmt> "dostmt" 191 * if <stmt> "ifstmt" 192 * switch <stmt> <stmt> 193 * decl <stmt> <stmt> 194 * "ifelse" <stmt> <stmt> 195 * for <stmt> <stmt> 196 * while <stmt> <stmt> 197 * "dostmt" while <stmt> 198 * 199 * On each reduction, ps.i_l_follow (the indentation for the following line) 200 * is set to the indentation level associated with the old TOS. 201 * 202 * PARAMETERS: None 203 * 204 * RETURNS: Nothing 205 * 206 * GLOBALS: ps.cstk ps.i_l_follow = ps.il ps.p_stack = ps.tos = 207 * 208 * CALLS: None 209 * 210 * CALLED BY: parse 211 * 212 * HISTORY: initial coding November 1976 D A Willcox of CAC 213 * 214 */ 215 /*----------------------------------------------*\ 216 | REDUCTION PHASE | 217 \*----------------------------------------------*/ 218 reduce() 219 { 220 221 register int i; 222 223 for (;;) { /* keep looping until there is nothing left to 224 * reduce */ 225 226 switch (ps.p_stack[ps.tos]) { 227 228 case stmt: 229 switch (ps.p_stack[ps.tos - 1]) { 230 231 case stmt: 232 case stmtl: 233 /* stmtl stmt or stmt stmt */ 234 ps.p_stack[--ps.tos] = stmtl; 235 break; 236 237 case dolit: /* <do> <stmt> */ 238 ps.p_stack[--ps.tos] = dohead; 239 ps.i_l_follow = ps.il[ps.tos]; 240 break; 241 242 case ifstmt: 243 /* <if> <stmt> */ 244 ps.p_stack[--ps.tos] = ifhead; 245 for (i = ps.tos - 1; 246 ( 247 ps.p_stack[i] != stmt 248 && 249 ps.p_stack[i] != stmtl 250 && 251 ps.p_stack[i] != lbrace 252 ); 253 --i); 254 ps.i_l_follow = ps.il[i]; 255 /* 256 * for the time being, we will assume that there is no else on 257 * this if, and set the indentation level accordingly. If an 258 * else is scanned, it will be fixed up later 259 */ 260 break; 261 262 case swstmt: 263 /* <switch> <stmt> */ 264 case_ind = ps.cstk[ps.tos - 1]; 265 266 case decl: /* finish of a declaration */ 267 case elsehead: 268 /* <<if> <stmt> else> <stmt> */ 269 case forstmt: 270 /* <for> <stmt> */ 271 case whilestmt: 272 /* <while> <stmt> */ 273 ps.p_stack[--ps.tos] = stmt; 274 ps.i_l_follow = ps.il[ps.tos]; 275 break; 276 277 default: /* <anything else> <stmt> */ 278 return; 279 280 } /* end of section for <stmt> on top of stack */ 281 break; 282 283 case whilestmt: /* while (...) on top */ 284 if (ps.p_stack[ps.tos - 1] == dohead) { 285 /* it is termination of a do while */ 286 ps.p_stack[--ps.tos] = stmt; 287 break; 288 } 289 else 290 return; 291 292 default: /* anything else on top */ 293 return; 294 295 } 296 } 297 } 298