sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
minix/commands/elvis/regexp.c
Ben Gras 9865aeaa79 Initial revision
2005-04-21 14:53:53 +00:00

934 lines
18 KiB
C
Executable file
Raw Blame History

/* regexp.c */
/* This file contains the code that compiles regular expressions and executes
* them. It supports the same syntax and features as vi's regular expression
* code. Specifically, the meta characters are:
* ^ matches the beginning of a line
* $ matches the end of a line
* \< matches the beginning of a word
* \> matches the end of a word
* . matches any single character
* [] matches any character in a character class
* \( delimits the start of a subexpression
* \) delimits the end of a subexpression
* * repeats the preceding 0 or more times
* NOTE: You cannot follow a \) with a *.
*
* The physical structure of a compiled RE is as follows:
* - First, there is a one-byte value that says how many character classes
* are used in this regular expression
* - Next, each character class is stored as a bitmap that is 256 bits
* (32 bytes) long.
* - A mixture of literal characters and compiled meta characters follows.
* This begins with M_BEGIN(0) and ends with M_END(0). All meta chars
* are stored as a \n followed by a one-byte code, so they take up two
* bytes apiece. Literal characters take up one byte apiece. \n can't
* be used as a literal character.
*
* If NO_MAGIC is defined, then a different set of functions is used instead.
* That right, this file contains TWO versions of the code.
*/
#include <setjmp.h>
#include "config.h"
#include "ctype.h"
#include "vi.h"
#include "regexp.h"
static char *previous; /* the previous regexp, used when null regexp is given */
#ifndef NO_MAGIC
/* THE REAL REGEXP PACKAGE IS USED UNLESS "NO_MAGIC" IS DEFINED */
/* These are used to classify or recognize meta-characters */
#define META '\0'
#define BASE_META(m) ((m) - 256)
#define INT_META(c) ((c) + 256)
#define IS_META(m) ((m) >= 256)
#define IS_CLASS(m) ((m) >= M_CLASS(0) && (m) <= M_CLASS(9))
#define IS_START(m) ((m) >= M_START(0) && (m) <= M_START(9))
#define IS_END(m) ((m) >= M_END(0) && (m) <= M_END(9))
#define IS_CLOSURE(m) ((m) >= M_SPLAT && (m) <= M_RANGE)
#define ADD_META(s,m) (*(s)++ = META, *(s)++ = BASE_META(m))
#define GET_META(s) (*(s) == META ? INT_META(*++(s)) : *s)
/* These are the internal codes used for each type of meta-character */
#define M_BEGLINE 256 /* internal code for ^ */
#define M_ENDLINE 257 /* internal code for $ */
#define M_BEGWORD 258 /* internal code for \< */
#define M_ENDWORD 259 /* internal code for \> */
#define M_ANY 260 /* internal code for . */
#define M_SPLAT 261 /* internal code for * */
#define M_PLUS 262 /* internal code for \+ */
#define M_QMARK 263 /* internal code for \? */
#define M_RANGE 264 /* internal code for \{ */
#define M_CLASS(n) (265+(n)) /* internal code for [] */
#define M_START(n) (275+(n)) /* internal code for \( */
#define M_END(n) (285+(n)) /* internal code for \) */
/* These are used during compilation */
static int class_cnt; /* used to assign class IDs */
static int start_cnt; /* used to assign start IDs */
static int end_stk[NSUBEXP];/* used to assign end IDs */
static int end_sp;
static char *retext; /* points to the text being compiled */
/* error-handling stuff */
jmp_buf errorhandler;
#define FAIL(why) regerror(why); longjmp(errorhandler, 1)
/* This function builds a bitmap for a particular class */
static char *makeclass(text, bmap)
REG char *text; /* start of the class */
REG char *bmap; /* the bitmap */
{
REG int i;
int complement = 0;
/* zero the bitmap */
for (i = 0; bmap && i < 32; i++)
{
bmap[i] = 0;
}
/* see if we're going to complement this class */
if (*text == '^')
{
text++;
complement = 1;
}
/* add in the characters */
while (*text && *text != ']')
{
/* is this a span of characters? */
if (text[1] == '-' && text[2])
{
/* spans can't be backwards */
if (text[0] > text[2])
{
FAIL("Backwards span in []");
}
/* add each character in the span to the bitmap */
for (i = text[0]; bmap && i <= text[2]; i++)
{
bmap[i >> 3] |= (1 << (i & 7));
}
/* move past this span */
text += 3;
}
else
{
/* add this single character to the span */
i = *text++;
if (bmap)
{
bmap[i >> 3] |= (1 << (i & 7));
}
}
}
/* make sure the closing ] is missing */
if (*text++ != ']')
{
FAIL("] missing");
}
/* if we're supposed to complement this class, then do so */
if (complement && bmap)
{
for (i = 0; i < 32; i++)
{
bmap[i] = ~bmap[i];
}
}
return text;
}
/* This function gets the next character or meta character from a string.
* The pointer is incremented by 1, or by 2 for \-quoted characters. For [],
* a bitmap is generated via makeclass() (if re is given), and the
* character-class text is skipped.
*/
static int gettoken(sptr, re)
char **sptr;
regexp *re;
{
int c;
c = **sptr;
++*sptr;
if (c == '\\')
{
c = **sptr;
++*sptr;
switch (c)
{
case '<':
return M_BEGWORD;
case '>':
return M_ENDWORD;
case '(':
if (start_cnt >= NSUBEXP)
{
FAIL("Too many \\(s");
}
end_stk[end_sp++] = start_cnt;
return M_START(start_cnt++);
case ')':
if (end_sp <= 0)
{
FAIL("Mismatched \\)");
}
return M_END(end_stk[--end_sp]);
case '*':
return (*o_magic ? c : M_SPLAT);
case '.':
return (*o_magic ? c : M_ANY);
case '+':
return M_PLUS;
case '?':
return M_QMARK;
#ifndef CRUNCH
case '{':
return M_RANGE;
#endif
default:
return c;
}
}
else if (*o_magic)
{
switch (c)
{
case '^':
if (*sptr == retext + 1)
{
return M_BEGLINE;
}
return c;
case '$':
if (!**sptr)
{
return M_ENDLINE;
}
return c;
case '.':
return M_ANY;
case '*':
return M_SPLAT;
case '[':
/* make sure we don't have too many classes */
if (class_cnt >= 10)
{
FAIL("Too many []s");
}
/* process the character list for this class */
if (re)
{
/* generate the bitmap for this class */
*sptr = makeclass(*sptr, re->program + 1 + 32 * class_cnt);
}
else
{
/* skip to end of the class */
*sptr = makeclass(*sptr, (char *)0);
}
return M_CLASS(class_cnt++);
default:
return c;
}
}
else /* unquoted nomagic */
{
switch (c)
{
case '^':
if (*sptr == retext + 1)
{
return M_BEGLINE;
}
return c;
case '$':
if (!**sptr)
{
return M_ENDLINE;
}
return c;
default:
return c;
}
}
/*NOTREACHED*/
}
/* This function calculates the number of bytes that will be needed for a
* compiled RE. Its argument is the uncompiled version. It is not clever
* about catching syntax errors; that is done in a later pass.
*/
static unsigned calcsize(text)
char *text;
{
unsigned size;
int token;
retext = text;
class_cnt = 0;
start_cnt = 1;
end_sp = 0;
size = 5;
while ((token = gettoken(&text, (regexp *)0)) != 0)
{
if (IS_CLASS(token))
{
size += 34;
}
#ifndef CRUNCH
else if (token == M_RANGE)
{
size += 4;
while ((token = gettoken(&text, (regexp *)0)) != 0
&& token != '}')
{
}
if (!token)
{
return size;
}
}
#endif
else if (IS_META(token))
{
size += 2;
}
else
{
size++;
}
}
return size;
}
/* This function compiles a regexp. */
regexp *regcomp(exp)
char *exp;
{
int needfirst;
unsigned size;
int token;
int peek;
char *build;
regexp *re;
#ifndef CRUNCH
int from;
int to;
int digit;
#endif
/* prepare for error handling */
re = (regexp *)0;
if (setjmp(errorhandler))
{
if (re)
{
free(re);
}
return (regexp *)0;
}
/* if an empty regexp string was given, use the previous one */
if (*exp == 0)
{
if (!previous)
{
FAIL("No previous RE");
}
exp = previous;
}
else /* non-empty regexp given, so remember it */
{
if (previous)
free(previous);
previous = (char *)malloc((unsigned)(strlen(exp) + 1));
if (previous)
strcpy(previous, exp);
}
/* allocate memory */
class_cnt = 0;
start_cnt = 1;
end_sp = 0;
retext = exp;
size = calcsize(exp) + sizeof(regexp) + 10; /* !!! 10 bytes for slop */
#ifdef lint
re = ((regexp *)0) + size;
#else
re = (regexp *)malloc((unsigned)size);
#endif
if (!re)
{
FAIL("Not enough memory for this RE");
}
/* compile it */
build = &re->program[1 + 32 * class_cnt];
re->program[0] = class_cnt;
for (token = 0; token < NSUBEXP; token++)
{
re->startp[token] = re->endp[token] = (char *)0;
}
re->first = 0;
re->bol = 0;
re->minlen = 0;
needfirst = 1;
class_cnt = 0;
start_cnt = 1;
end_sp = 0;
retext = exp;
for (token = M_START(0), peek = gettoken(&exp, re);
token;
token = peek, peek = gettoken(&exp, re))
{
/* special processing for the closure operator */
if (IS_CLOSURE(peek))
{
/* detect misuse of closure operator */
if (IS_START(token))
{
FAIL("Closure operator follows nothing");
}
else if (IS_META(token) && token != M_ANY && !IS_CLASS(token))
{
FAIL("Closure operators can only follow a normal character or . or []");
}
#ifndef CRUNCH
/* if \{ \} then read the range */
if (peek == M_RANGE)
{
from = 0;
for (digit = gettoken(&exp, re);
!IS_META(digit) && isdigit(digit);
digit = gettoken(&exp, re))
{
from = from * 10 + digit - '0';
}
if (digit == '}')
{
to = from;
}
else if (digit == ',')
{
to = 0;
for (digit = gettoken(&exp, re);
!IS_META(digit) && isdigit(digit);
digit = gettoken(&exp, re))
{
to = to * 10 + digit - '0';
}
if (to == 0)
{
to = 255;
}
}
if (digit != '}')
{
FAIL("Bad characters after \\{");
}
else if (to < from || to == 0 || from >= 255)
{
FAIL("Invalid range for \\{ \\}");
}
re->minlen += from;
}
else
#endif
if (peek != M_SPLAT)
{
re->minlen++;
}
/* it is okay -- make it prefix instead of postfix */
ADD_META(build, peek);
#ifndef CRUNCH
if (peek == M_RANGE)
{
*build++ = from;
*build++ = (to < 255 ? to : 255);
}
#endif
/* take care of "needfirst" - is this the first char? */
if (needfirst && peek == M_PLUS && !IS_META(token))
{
re->first = token;
}
needfirst = 0;
/* we used "peek" -- need to refill it */
peek = gettoken(&exp, re);
if (IS_CLOSURE(peek))
{
FAIL("* or \\+ or \\? doubled up");
}
}
else if (!IS_META(token))
{
/* normal char is NOT argument of closure */
if (needfirst)
{
re->first = token;
needfirst = 0;
}
re->minlen++;
}
else if (token == M_ANY || IS_CLASS(token))
{
/* . or [] is NOT argument of closure */
needfirst = 0;
re->minlen++;
}
/* the "token" character is not closure -- process it normally */
if (token == M_BEGLINE)
{
/* set the BOL flag instead of storing M_BEGLINE */
re->bol = 1;
}
else if (IS_META(token))
{
ADD_META(build, token);
}
else
{
*build++ = token;
}
}
/* end it with a \) which MUST MATCH the opening \( */
ADD_META(build, M_END(0));
if (end_sp > 0)
{
FAIL("Not enough \\)s");
}
return re;
}
/*---------------------------------------------------------------------------*/
/* This function checks for a match between a character and a token which is
* known to represent a single character. It returns 0 if they match, or
* 1 if they don't.
*/
int match1(re, ch, token)
regexp *re;
REG char ch;
REG int token;
{
if (!ch)
{
/* the end of a line can't match any RE of width 1 */
return 1;
}
if (token == M_ANY)
{
return 0;
}
else if (IS_CLASS(token))
{
if (re->program[1 + 32 * (token - M_CLASS(0)) + (ch >> 3)] & (1 << (ch & 7)))
return 0;
}
else if (ch == token || *o_ignorecase && tolower(ch) == tolower(token))
{
return 0;
}
return 1;
}
/* This function checks characters up to and including the next closure, at
* which point it does a recursive call to check the rest of it. This function
* returns 0 if everything matches, or 1 if something doesn't match.
*/
int match(re, str, prog, here)
regexp *re; /* the regular expression */
char *str; /* the string */
REG char *prog; /* a portion of re->program, an compiled RE */
REG char *here; /* a portion of str, the string to compare it to */
{
REG int token; /* the roken pointed to by prog */
REG int nmatched;/* counter, used during closure matching */
REG int closure;/* the token denoting the type of closure */
int from; /* minimum number of matches in closure */
int to; /* maximum number of matches in closure */
for (token = GET_META(prog); !IS_CLOSURE(token); prog++, token = GET_META(prog))
{
switch (token)
{
/*case M_BEGLINE: can't happen; re->bol is used instead */
case M_ENDLINE:
if (*here)
return 1;
break;
case M_BEGWORD:
if (here != str &&
(here[-1] == '_' || isalnum(here[-1])))
return 1;
break;
case M_ENDWORD:
if (here[0] == '_' || isalnum(here[0]))
return 1;
break;
case M_START(0):
case M_START(1):
case M_START(2):
case M_START(3):
case M_START(4):
case M_START(5):
case M_START(6):
case M_START(7):
case M_START(8):
case M_START(9):
re->startp[token - M_START(0)] = (char *)here;
break;
case M_END(0):
case M_END(1):
case M_END(2):
case M_END(3):
case M_END(4):
case M_END(5):
case M_END(6):
case M_END(7):
case M_END(8):
case M_END(9):
re->endp[token - M_END(0)] = (char *)here;
if (token == M_END(0))
{
return 0;
}
break;
default: /* literal, M_CLASS(n), or M_ANY */
if (match1(re, *here, token) != 0)
return 1;
here++;
}
}
/* C L O S U R E */
/* step 1: see what we have to match against, and move "prog" to point
* to the remainder of the compiled RE.
*/
closure = token;
prog++;
switch (closure)
{
case M_SPLAT:
from = 0;
to = strlen(str); /* infinity */
break;
case M_PLUS:
from = 1;
to = strlen(str); /* infinity */
break;
case M_QMARK:
from = 0;
to = 1;
break;
#ifndef CRUNCH
case M_RANGE:
from = UCHAR(*prog++);
to = UCHAR(*prog++);
if (to == 255)
{
to = strlen(str); /* infinity */
}
break;
#endif
}
token = GET_META(prog);
prog++;
/* step 2: see how many times we can match that token against the string */
for (nmatched = 0;
nmatched < to && *here && match1(re, *here, token) == 0;
nmatched++, here++)
{
}
/* step 3: try to match the remainder, and back off if it doesn't */
while (nmatched >= from && match(re, str, prog, here) != 0)
{
nmatched--;
here--;
}
/* so how did it work out? */
if (nmatched >= from)
return 0;
return 1;
}
/* This function searches through a string for text that matches an RE. */
int regexec(re, str, bol)
regexp *re; /* the compiled regexp to search for */
char *str; /* the string to search through */
int bol; /* boolean: does str start at the beginning of a line? */
{
char *prog; /* the entry point of re->program */
int len; /* length of the string */
REG char *here;
/* if must start at the beginning of a line, and this isn't, then fail */
if (re->bol && !bol)
{
return 0;
}
len = strlen(str);
prog = re->program + 1 + 32 * re->program[0];
/* search for the RE in the string */
if (re->bol)
{
/* must occur at BOL */
if ((re->first
&& match1(re, *(char *)str, re->first))/* wrong first letter? */
|| len < re->minlen /* not long enough? */
|| match(re, (char *)str, prog, str)) /* doesn't match? */
return 0; /* THEN FAIL! */
}
#ifndef CRUNCH
else if (!*o_ignorecase)
{
/* can occur anywhere in the line, noignorecase */
for (here = (char *)str;
(re->first && re->first != *here)
|| match(re, (char *)str, prog, here);
here++, len--)
{
if (len < re->minlen)
return 0;
}
}
#endif
else
{
/* can occur anywhere in the line, ignorecase */
for (here = (char *)str;
(re->first && match1(re, *here, (int)re->first))
|| match(re, (char *)str, prog, here);
here++, len--)
{
if (len < re->minlen)
return 0;
}
}
/* if we didn't fail, then we must have succeeded */
return 1;
}
/*============================================================================*/
#else /* NO_MAGIC */
regexp *regcomp(exp)
char *exp;
{
char *src;
char *dest;
regexp *re;
int i;
/* allocate a big enough regexp structure */
#ifdef lint
re = (regexp *)0;
#else
re = (regexp *)malloc((unsigned)(strlen(exp) + 1 + sizeof(struct regexp)));
#endif
if (!re)
{
regerror("Could not malloc a regexp structure");
return (regexp *)0;
}
/* initialize all fields of the structure */
for (i = 0; i < NSUBEXP; i++)
{
re->startp[i] = re->endp[i] = (char *)0;
}
re->minlen = 0;
re->first = 0;
re->bol = 0;
/* copy the string into it, translating ^ and $ as needed */
for (src = exp, dest = re->program + 1; *src; src++)
{
switch (*src)
{
case '^':
if (src == exp)
{
re->bol += 1;
}
else
{
*dest++ = '^';
re->minlen++;
}
break;
case '$':
if (!src[1])
{
re->bol += 2;
}
else
{
*dest++ = '$';
re->minlen++;
}
break;
case '\\':
if (src[1])
{
*dest++ = *++src;
re->minlen++;
}
else
{
regerror("extra \\ at end of regular expression");
}
break;
default:
*dest++ = *src;
re->minlen++;
}
}
*dest = '\0';
return re;
}
/* This "helper" function checks for a match at a given location. It returns
* 1 if it matches, 0 if it doesn't match here but might match later on in the
* string, or -1 if it could not possibly match
*/
static int reghelp(prog, string, bolflag)
struct regexp *prog;
char *string;
int bolflag;
{
char *scan;
char *str;
/* if ^, then require bolflag */
if ((prog->bol & 1) && !bolflag)
{
return -1;
}
/* if it matches, then it will start here */
prog->startp[0] = string;
/* compare, possibly ignoring case */
if (*o_ignorecase)
{
for (scan = &prog->program[1]; *scan; scan++, string++)
if (tolower(*scan) != tolower(*string))
return *string ? 0 : -1;
}
else
{
for (scan = &prog->program[1]; *scan; scan++, string++)
if (*scan != *string)
return *string ? 0 : -1;
}
/* if $, then require string to end here, too */
if ((prog->bol & 2) && *string)
{
return 0;
}
/* if we get to here, it matches */
prog->endp[0] = string;
return 1;
}
int regexec(prog, string, bolflag)
struct regexp *prog;
char *string;
int bolflag;
{
int rc;
/* keep trying to match it */
for (rc = reghelp(prog, string, bolflag); rc == 0; rc = reghelp(prog, string, 0))
{
string++;
}
/* did we match? */
return rc == 1;
}
#endif
Reference in a new issue View git blame Copy permalink