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1 | /* $RCSfile: regcomp.h,v $$Revision: 4.0.1.1 $$Date: 91/06/07 11:49:40 $ |
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2 | * |
3 | * $Log: regcomp.h,v $ |
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4 | * Revision 4.0.1.1 91/06/07 11:49:40 lwall |
5 | * patch4: no change |
6 | * |
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7 | * Revision 4.0 91/03/20 01:39:09 lwall |
8 | * 4.0 baseline. |
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9 | * |
10 | */ |
11 | |
12 | /* |
13 | * The "internal use only" fields in regexp.h are present to pass info from |
14 | * compile to execute that permits the execute phase to run lots faster on |
15 | * simple cases. They are: |
16 | * |
17 | * regstart str that must begin a match; Nullch if none obvious |
18 | * reganch is the match anchored (at beginning-of-line only)? |
19 | * regmust string (pointer into program) that match must include, or NULL |
20 | * [regmust changed to STR* for bminstr()--law] |
21 | * regmlen length of regmust string |
22 | * [regmlen not used currently] |
23 | * |
24 | * Regstart and reganch permit very fast decisions on suitable starting points |
25 | * for a match, cutting down the work a lot. Regmust permits fast rejection |
26 | * of lines that cannot possibly match. The regmust tests are costly enough |
27 | * that regcomp() supplies a regmust only if the r.e. contains something |
28 | * potentially expensive (at present, the only such thing detected is * or + |
29 | * at the start of the r.e., which can involve a lot of backup). Regmlen is |
30 | * supplied because the test in regexec() needs it and regcomp() is computing |
31 | * it anyway. |
32 | * [regmust is now supplied always. The tests that use regmust have a |
33 | * heuristic that disables the test if it usually matches.] |
34 | * |
35 | * [In fact, we now use regmust in many cases to locate where the search |
36 | * starts in the string, so if regback is >= 0, the regmust search is never |
37 | * wasted effort. The regback variable says how many characters back from |
38 | * where regmust matched is the earliest possible start of the match. |
39 | * For instance, /[a-z].foo/ has a regmust of 'foo' and a regback of 2.] |
40 | */ |
41 | |
42 | /* |
43 | * Structure for regexp "program". This is essentially a linear encoding |
44 | * of a nondeterministic finite-state machine (aka syntax charts or |
45 | * "railroad normal form" in parsing technology). Each node is an opcode |
46 | * plus a "next" pointer, possibly plus an operand. "Next" pointers of |
47 | * all nodes except BRANCH implement concatenation; a "next" pointer with |
48 | * a BRANCH on both ends of it is connecting two alternatives. (Here we |
49 | * have one of the subtle syntax dependencies: an individual BRANCH (as |
50 | * opposed to a collection of them) is never concatenated with anything |
51 | * because of operator precedence.) The operand of some types of node is |
52 | * a literal string; for others, it is a node leading into a sub-FSM. In |
53 | * particular, the operand of a BRANCH node is the first node of the branch. |
54 | * (NB this is *not* a tree structure: the tail of the branch connects |
55 | * to the thing following the set of BRANCHes.) The opcodes are: |
56 | */ |
57 | |
58 | /* definition number opnd? meaning */ |
59 | #define END 0 /* no End of program. */ |
60 | #define BOL 1 /* no Match "" at beginning of line. */ |
61 | #define EOL 2 /* no Match "" at end of line. */ |
62 | #define ANY 3 /* no Match any one character. */ |
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63 | #define ANYOF 4 /* str Match character in (or not in) this class. */ |
64 | #define CURLY 5 /* str Match this simple thing {n,m} times. */ |
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65 | #define BRANCH 6 /* node Match this alternative, or the next... */ |
66 | #define BACK 7 /* no Match "", "next" ptr points backward. */ |
67 | #define EXACTLY 8 /* str Match this string (preceded by length). */ |
68 | #define NOTHING 9 /* no Match empty string. */ |
69 | #define STAR 10 /* node Match this (simple) thing 0 or more times. */ |
70 | #define PLUS 11 /* node Match this (simple) thing 1 or more times. */ |
71 | #define ALNUM 12 /* no Match any alphanumeric character */ |
72 | #define NALNUM 13 /* no Match any non-alphanumeric character */ |
73 | #define BOUND 14 /* no Match "" at any word boundary */ |
74 | #define NBOUND 15 /* no Match "" at any word non-boundary */ |
75 | #define SPACE 16 /* no Match any whitespace character */ |
76 | #define NSPACE 17 /* no Match any non-whitespace character */ |
77 | #define DIGIT 18 /* no Match any numeric character */ |
78 | #define NDIGIT 19 /* no Match any non-numeric character */ |
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79 | #define REF 20 /* num Match some already matched string */ |
80 | #define OPEN 21 /* num Mark this point in input as start of #n. */ |
81 | #define CLOSE 22 /* num Analogous to OPEN. */ |
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82 | |
83 | /* |
84 | * Opcode notes: |
85 | * |
86 | * BRANCH The set of branches constituting a single choice are hooked |
87 | * together with their "next" pointers, since precedence prevents |
88 | * anything being concatenated to any individual branch. The |
89 | * "next" pointer of the last BRANCH in a choice points to the |
90 | * thing following the whole choice. This is also where the |
91 | * final "next" pointer of each individual branch points; each |
92 | * branch starts with the operand node of a BRANCH node. |
93 | * |
94 | * BACK Normal "next" pointers all implicitly point forward; BACK |
95 | * exists to make loop structures possible. |
96 | * |
97 | * STAR,PLUS '?', and complex '*' and '+', are implemented as circular |
98 | * BRANCH structures using BACK. Simple cases (one character |
99 | * per match) are implemented with STAR and PLUS for speed |
100 | * and to minimize recursive plunges. |
101 | * |
102 | * OPEN,CLOSE ...are numbered at compile time. |
103 | */ |
104 | |
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105 | #ifndef DOINIT |
106 | extern char regarglen[]; |
107 | #else |
108 | char regarglen[] = {0,0,0,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,2,2}; |
109 | #endif |
110 | |
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111 | /* The following have no fixed length. */ |
112 | #ifndef DOINIT |
113 | extern char varies[]; |
114 | #else |
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115 | char varies[] = {BRANCH,BACK,STAR,PLUS,CURLY,REF,0}; |
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116 | #endif |
117 | |
118 | /* The following always have a length of 1. */ |
119 | #ifndef DOINIT |
120 | extern char simple[]; |
121 | #else |
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122 | char simple[] = {ANY,ANYOF,ALNUM,NALNUM,SPACE,NSPACE,DIGIT,NDIGIT,0}; |
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123 | #endif |
124 | |
125 | EXT char regdummy; |
126 | |
127 | /* |
128 | * A node is one char of opcode followed by two chars of "next" pointer. |
129 | * "Next" pointers are stored as two 8-bit pieces, high order first. The |
130 | * value is a positive offset from the opcode of the node containing it. |
131 | * An operand, if any, simply follows the node. (Note that much of the |
132 | * code generation knows about this implicit relationship.) |
133 | * |
134 | * Using two bytes for the "next" pointer is vast overkill for most things, |
135 | * but allows patterns to get big without disasters. |
136 | * |
137 | * [If REGALIGN is defined, the "next" pointer is always aligned on an even |
138 | * boundary, and reads the offset directly as a short. Also, there is no |
139 | * special test to reverse the sign of BACK pointers since the offset is |
140 | * stored negative.] |
141 | */ |
142 | |
143 | #ifndef gould |
144 | #ifndef cray |
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145 | #ifndef eta10 |
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146 | #define REGALIGN |
147 | #endif |
148 | #endif |
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149 | #endif |
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150 | |
151 | #define OP(p) (*(p)) |
152 | |
153 | #ifndef lint |
154 | #ifdef REGALIGN |
155 | #define NEXT(p) (*(short*)(p+1)) |
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156 | #define ARG1(p) (*(unsigned short*)(p+3)) |
157 | #define ARG2(p) (*(unsigned short*)(p+5)) |
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158 | #else |
159 | #define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377)) |
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160 | #define ARG1(p) (((*((p)+3)&0377)<<8) + (*((p)+4)&0377)) |
161 | #define ARG2(p) (((*((p)+5)&0377)<<8) + (*((p)+6)&0377)) |
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162 | #endif |
163 | #else /* lint */ |
164 | #define NEXT(p) 0 |
165 | #endif /* lint */ |
166 | |
167 | #define OPERAND(p) ((p) + 3) |
168 | |
169 | #ifdef REGALIGN |
170 | #define NEXTOPER(p) ((p) + 4) |
171 | #else |
172 | #define NEXTOPER(p) ((p) + 3) |
173 | #endif |
174 | |
175 | #define MAGIC 0234 |
176 | |
177 | /* |
178 | * Utility definitions. |
179 | */ |
180 | #ifndef lint |
181 | #ifndef CHARBITS |
182 | #define UCHARAT(p) ((int)*(unsigned char *)(p)) |
183 | #else |
184 | #define UCHARAT(p) ((int)*(p)&CHARBITS) |
185 | #endif |
186 | #else /* lint */ |
187 | #define UCHARAT(p) regdummy |
188 | #endif /* lint */ |
189 | |
190 | #define FAIL(m) fatal("/%s/: %s",regprecomp,m) |
191 | |
192 | char *regnext(); |
193 | #ifdef DEBUGGING |
194 | void regdump(); |
195 | char *regprop(); |
196 | #endif |
197 | |