/*
** 2012-11-13
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
******************************************************************************
**
** The code in this file implements a compact but reasonably
** efficient regular-expression matcher for posix extended regular
** expressions against UTF8 text. The following syntax is supported:
**
** X* zero or more occurrences of X
** X+ one or more occurrences of X
** X? zero or one occurrences of X
** X{p,q} between p and q occurrences of X
** (X) match X
** X|Y X or Y
** ^X X occurring at the beginning of the string
** X$ X occurring at the end of the string
** . Match any single character
** \c Character c where c is one of \{}()[]|*+?.
** \c C-language escapes for c in afnrtv. ex: \t or \n
** \uXXXX Where XXXX is exactly 4 hex digits, unicode value XXXX
** \xXXX Where XXX is any number of hex digits, unicode value XXX
** [abc] Any single character from the set abc
** [^abc] Any single character not in the set abc
** [a-z] Any single character in the range a-z
** [^a-z] Any single character not in the range a-z
** \b Word boundary
** \w Word character. [A-Za-z0-9_]
** \W Non-word character
** \d Digit
** \D Non-digit
** \s Whitespace character
** \S Non-whitespace character
**
** A nondeterministic finite automaton (NFA) is used for matching, so the
** performance is bounded by O(N*M) where N is the size of the regular
** expression and M is the size of the input string. The matcher never
** exhibits exponential behavior. Note that the X{p,q} operator expands
** to p copies of X following by q-p copies of X? and that the size of the
** regular expression in the O(N*M) performance bound is computed after
** this expansion.
*/
#include <string.h>
#include <stdlib.h>
#include "sqlite3.h"
/* The end-of-input character */
#define RE_EOF 0 /* End of input */
/* The NFA is implemented as sequence of opcodes taken from the following
** set. Each opcode has a single integer argument.
*/
#define RE_OP_MATCH 1 /* Match the one character in the argument */
#define RE_OP_ANY 2 /* Match any one character. (Implements ".") */
#define RE_OP_ANYSTAR 3 /* Special optimized version of .* */
#define RE_OP_FORK 4 /* Continue to both next and opcode at iArg */
#define RE_OP_GOTO 5 /* Jump to opcode at iArg */
#define RE_OP_ACCEPT 6 /* Halt and indicate a successful match */
#define RE_OP_CC_INC 7 /* Beginning of a [...] character class */
#define RE_OP_CC_EXC 8 /* Beginning of a [^...] character class */
#define RE_OP_CC_VALUE 9 /* Single value in a character class */
#define RE_OP_CC_RANGE 10 /* Range of values in a character class */
#define RE_OP_WORD 11 /* Perl word character [A-Za-z0-9_] */
#define RE_OP_NOTWORD 12 /* Not a perl word character */
#define RE_OP_DIGIT 13 /* digit: [0-9] */
#define RE_OP_NOTDIGIT 14 /* Not a digit */
#define RE_OP_SPACE 15 /* space: [ \t\n\r\v\f] */
#define RE_OP_NOTSPACE 16 /* Not a digit */
#define RE_OP_BOUNDARY 17 /* Boundary between word and non-word */
/* Each opcode is a "state" in the NFA */
typedef unsigned short ReStateNumber;
/* Because this is an NFA and not a DFA, multiple states can be active at
** once. An instance of the following object records all active states in
** the NFA. The implementation is optimized for the common case where the
** number of actives states is small.
*/
typedef struct ReStateSet {
unsigned nState; /* Number of current states */
ReStateNumber *aState; /* Current states */
} ReStateSet;
/* A compiled NFA (or an NFA that is in the process of being compiled) is
** an instance of the following object.
*/
typedef struct ReCompiled {
const unsigned char *zIn; /* Regular expression text */
const char *zErr; /* Error message to return */
char *aOp; /* Operators for the virtual machine */
int *aArg; /* Arguments to each operator */
char zInit[12]; /* Initial text to match */
int nInit; /* Number of characters in zInit */
unsigned nState; /* Number of entries in aOp[] and aArg[] */
unsigned nAlloc; /* Slots allocated for aOp[] and aArg[] */
} ReCompiled;
/* Add a state to the given state set if it is not already there */
static void re_add_state(ReStateSet *pSet, int newState){
unsigned i;
for(i=0; i<pSet->nState; i++) if( pSet->aState[i]==newState ) return;
pSet->aState[pSet->nState++] = newState;
}
/* Extract the next unicode character from *pzIn and return it. Advance
** *pzIn to the first byte past the end of the character returned. To
** be clear: this routine converts utf8 to unicode. This routine is
** optimized for the common case where the next character is a single byte.
*/
static unsigned re_next_char(const unsigned char **pzIn){
unsigned c = **pzIn;
if( c>0 ) (*pzIn)++;
if( c>0x80 ){
if( (c&0xe0)==0xc0 && ((*pzIn)[0]&0xc0)==0x80 ){
c = (c&0x1f)<<6 | ((*pzIn)[0]&0x3f);
(*pzIn)++;
if( c<0x80 ) c = 0xfffd;
}else if( (c&0xf0)==0xe0 && ((*pzIn)[0]&0xc0)==0x80
&& ((*pzIn)[1]&0xc0)==0x80 ){
c = (c&0x0f)<<12 | (((*pzIn)[0]&0x3f)<<6) | ((*pzIn)[1]&0x3f);
*pzIn += 2;
if( c<0x3ff || (c>=0xd800 && c<=0xdfff) ) c = 0xfffd;
}else if( (c&0xf8)==0xf0 && ((*pzIn)[0]&0xc0)==0x80
&& ((*pzIn)[1]&0xc0)==0x80 && ((*pzIn)[2]&0xc0)==0x80 ){
c = (c&0x07)<<18 | (((*pzIn)[0]&0x3f)<<12) | (((*pzIn)[1]&0x3f)<<6)
| ((*pzIn)[2]&0x3f);
*pzIn += 3;
if( c<0xffff ) c = 0xfffd;
}else{
c = 0xfffd;
}
}
return c;
}
/* Return true if c is a perl "word" character: [A-Za-z0-9_] */
static int re_word_char(int c){
return (c>='0' && c<='9') || (c>='a' && c<='z')
|| (c>='A' && c<='Z') || c=='_';
}
/* Return true if c is a "digit" character: [0-9] */
static int re_digit_char(int c){
return (c>='0' && c<='9');
}
/* Return true if c is a perl "space" character: [ \t\r\n\v\f] */
static int re_space_char(int c){
return c==' ' || c=='\t' || c=='\n' || c=='\v' || c=='\f';
}
/* Run a compiled regular expression on the zero-terminated input
** string zIn[]. Return true on a match and false if there is no match.
*/
static int re_exec(ReCompiled *pRe, const unsigned char *zIn){
ReStateSet aStateSet[2], *pThis, *pNext;
ReStateNumber aSpace[100];
ReStateNumber *pToFree;
unsigned int i = 0;
unsigned int iSwap = 0;
int c = RE_EOF+1;
int cPrev = 0;
int rc = 0;
if( pRe->nInit ){
unsigned char x = pRe->zInit[0];
while( zIn[0] && (zIn[0]!=x || memcmp(zIn, pRe->zInit, pRe->nInit)!=0) ){
zIn++;
}
if( zIn[0]==0 ) return 0;
}
if( pRe->nState<=(sizeof(aSpace)/(sizeof(aSpace[0])*2)) ){
pToFree = 0;
aStateSet[0].aState = aSpace;
}else{
pToFree = malloc( sizeof(ReStateNumber)*2*pRe->nState );
if( pToFree==0 ) return -1;
aStateSet[0].aState = pToFree;
}
aStateSet[1].aState = &aStateSet[0].aState[pRe->nState];
pNext = &aStateSet[1];
pNext->nState = 0;
re_add_state(pNext, 0);
while( c!=RE_EOF && pNext->nState>0 ){
cPrev = c;
c = re_next_char(&zIn);
pThis = pNext;
pNext = &aStateSet[iSwap];
iSwap = 1 - iSwap;
pNext->nState = 0;
for(i=0; i<pThis->nState; i++){
int x = pThis->aState[i];
switch( pRe->aOp[x] ){
case RE_OP_MATCH: {
if( pRe->aArg[x]==c ) re_add_state(pNext, x+1);
break;
}
case RE_OP_ANY: {
re_add_state(pNext, x+1);
break;
}
case RE_OP_WORD: {
if( re_word_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_NOTWORD: {
if( !re_word_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_DIGIT: {
if( re_digit_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_NOTDIGIT: {
if( !re_digit_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_SPACE: {
if( re_space_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_NOTSPACE: {
if( !re_space_char(c) ) re_add_state(pNext, x+1);
break;
}
case RE_OP_BOUNDARY: {
if( re_word_char(c)!=re_word_char(cPrev) ) re_add_state(pThis, x+1);
break;
}
case RE_OP_ANYSTAR: {
re_add_state(pNext, x);
re_add_state(pThis, x+1);
break;
}
case RE_OP_FORK: {
re_add_state(pThis, x+pRe->aArg[x]);
re_add_state(pThis, x+1);
break;
}
case RE_OP_GOTO: {
re_add_state(pThis, x+pRe->aArg[x]);
break;
}
case RE_OP_ACCEPT: {
rc = 1;
goto re_exec_end;
}
case RE_OP_CC_INC:
case RE_OP_CC_EXC: {
int j = 1;
int n = pRe->aArg[x];
int hit = 0;
for(j=1; j>0 && j<n; j++){
if( pRe->aOp[x+j]==RE_OP_CC_VALUE ){
if( pRe->aArg[x+j]==c ){
hit = 1;
j = -1;
}
}else{
if( pRe->aArg[x+j]<=c && pRe->aArg[x+j+1]>=c ){
hit = 1;
j = -1;
}else{
j++;
}
}
}
if( pRe->aOp[x]==RE_OP_CC_EXC ) hit = !hit;
if( hit ) re_add_state(pNext, x+n);
break;
}
}
}
}
for(i=0; i<pNext->nState; i++){
if( pRe->aOp[pNext->aState[i]]==RE_OP_ACCEPT ){ rc = 1; break; }
}
re_exec_end:
free(pToFree);
return rc;
}
/* Resize the opcode and argument arrays for an RE under construction.
*/
static int re_resize(ReCompiled *p, int N){
char *aOp;
int *aArg;
aOp = realloc(p->aOp, N*sizeof(p->aOp[0]));
if( aOp==0 ) return 1;
p->aOp = aOp;
aArg = realloc(p->aArg, N*sizeof(p->aArg[0]));
if( aArg==0 ) return 1;
p->aArg = aArg;
p->nAlloc = N;
return 0;
}
/* Insert a new opcode and argument into an RE under construction. The
** insertion point is just prior to existing opcode iBefore.
*/
static int re_insert(ReCompiled *p, int iBefore, int op, int arg){
int i;
if( p->nAlloc<=p->nState && re_resize(p, p->nAlloc*2) ) return 0;
for(i=p->nState; i>iBefore; i--){
p->aOp[i] = p->aOp[i-1];
p->aArg[i] = p->aArg[i-1];
}
p->nState++;
p->aOp[iBefore] = op;
p->aArg[iBefore] = arg;
return iBefore;
}
/* Append a new opcode and argument to the end of the RE under construction.
*/
static int re_append(ReCompiled *p, int op, int arg){
return re_insert(p, p->nState, op, arg);
}
/* Make a copy of N opcodes starting at iStart onto the end of the RE
** under construction.
*/
static void re_copy(ReCompiled *p, int iStart, int N){
if( p->nState+N>=p->nAlloc && re_resize(p, p->nAlloc*2+N) ) return;
memcpy(&p->aOp[p->nState], &p->aOp[iStart], N*sizeof(p->aOp[0]));
memcpy(&p->aArg[p->nState], &p->aArg[iStart], N*sizeof(p->aArg[0]));
p->nState += N;
}
/* Return true if c is a hexadecimal digit character: [0-9a-fA-F]
** If c is a hex digit, also set *pV = (*pV)*16 + valueof(c). If
** c is not a hex digit *pV is unchanged.
*/
static int re_hex(int c, int *pV){
if( c>='0' && c<='9' ){
c -= '0';
}else if( c>='a' && c<='f' ){
c -= 'a' - 10;
}else if( c>='A' && c<='F' ){
c -= 'A' - 10;
}else{
return 0;
}
*pV = (*pV)*16 + (c & 0xff);
return 1;
}
/* A backslash character has been seen, read the next character and
** return its intepretation.
*/
static unsigned re_esc_char(ReCompiled *p){
static const char zEsc[] = "afnrtv\\()*.+?[$^{|}]";
static const char zTrans[] = "\a\f\n\r\t\v";
int i, v = 0;
char c = p->zIn[0];
if( c=='u' ){
v = 0;
if( re_hex(p->zIn[1],&v)
&& re_hex(p->zIn[2],&v)
&& re_hex(p->zIn[3],&v)
&& re_hex(p->zIn[4],&v)
){
p->zIn += 5;
return v;
}
}
if( c=='x' ){
v = 0;
for(i=1; re_hex(p->zIn[i], &v); i++){}
if( i>1 ){
p->zIn += i;
return v;
}
}
for(i=0; zEsc[i] && zEsc[i]!=c; i++){}
if( zEsc[i] ){
if( i<6 ) c = zTrans[i];
p->zIn++;
}else{
p->zErr = "unknown \\ escape";
}
return c;
}
/* Forward declaration */
static const char *re_subcompile_string(ReCompiled*);
/* Compile RE text into a sequence of opcodes. Continue up to the
** first unmatched ")" character, then return. If an error is found,
** return a pointer to the error message string.
*/
static const char *re_subcompile_re(ReCompiled *p){
const char *zErr;
int iStart, iEnd, iGoto;
iStart = p->nState;
zErr = re_subcompile_string(p);
if( zErr ) return zErr;
while( p->zIn[0]=='|' ){
iEnd = p->nState;
re_insert(p, iStart, RE_OP_FORK, iEnd + 2 - iStart);
iGoto = re_append(p, RE_OP_GOTO, 0);
p->zIn++;
zErr = re_subcompile_string(p);
if( zErr ) return zErr;
p->aArg[iGoto] = p->nState - iGoto;
}
return 0;
}
/* Compile an element of regular expression text (anything that can be
** an operand to the "|" operator). Return NULL on success or a pointer
** to the error message if there is a problem.
*/
static const char *re_subcompile_string(ReCompiled *p){
int iPrev = -1;
int iStart;
unsigned c;
const char *zErr;
while( (c = re_next_char(&p->zIn))!=0 ){
iStart = p->nState;
switch( c ){
case '|':
case '$':
case ')': {
p->zIn--;
return 0;
}
case '(': {
zErr = re_subcompile_re(p);
if( zErr ) return zErr;
if( p->zIn[0]!=')' ) return "unmatched '('";
p->zIn++;
break;
}
case '.': {
if( p->zIn[0]=='*' ){
re_append(p, RE_OP_ANYSTAR, 0);
p->zIn++;
}else{
re_append(p, RE_OP_ANY, 0);
}
break;
}
case '*': {
if( iPrev<0 ) return "'*' without operand";
re_insert(p, iPrev, RE_OP_GOTO, p->nState - iPrev + 1);
re_append(p, RE_OP_FORK, iPrev - p->nState + 1);
break;
}
case '+': {
if( iPrev<0 ) return "'+' without operand";
re_append(p, RE_OP_FORK, iPrev - p->nState);
break;
}
case '?': {
if( iPrev<0 ) return "'?' without operand";
re_insert(p, iPrev, RE_OP_FORK, p->nState - iPrev+1);
break;
}
case '{': {
int m = 0, n = 0;
int sz, j;
if( iPrev<0 ) return "'{m,n}' without operand";
while( (c=p->zIn[0])>='0' && c<='9' ){ m = m*10 + c - '0'; p->zIn++; }
n = m;
if( c==',' ){
p->zIn++;
n = 0;
while( (c=p->zIn[0])>='0' && c<='9' ){ n = n*10 + c - '0'; p->zIn++; }
}
if( c!='}' ) return "unmatched '{'";
if( n>0 && n<m ) return "n less than m in '{m,n}'";
p->zIn++;
sz = p->nState - iPrev;
if( m==0 ){
if( n==0 ) return "both m and n are zero in '{m,n}'";
re_insert(p, iPrev, RE_OP_FORK, sz+1);
n--;
}else{
for(j=1; j<m; j++) re_copy(p, iPrev, sz);
}
for(j=m; j<n; j++){
re_append(p, RE_OP_FORK, sz+1);
re_copy(p, iPrev, sz);
}
if( n==0 && m>0 ){
re_append(p, RE_OP_FORK, -sz);
}
break;
}
case '[': {
int iFirst = p->nState;
if( p->zIn[0]=='^' ){
re_append(p, RE_OP_CC_EXC, 0);
p->zIn++;
}else{
re_append(p, RE_OP_CC_INC, 0);
}
while( (c = re_next_char(&p->zIn))!=0 ){
if( c=='[' && p->zIn[0]==':' ){
return "POSIX character classes not supported";
}
if( c=='\\' ) c = re_esc_char(p);
if( p->zIn[0]=='-' && p->zIn[1] ){
re_append(p, RE_OP_CC_RANGE, c);
p->zIn++;
c = re_next_char(&p->zIn);
if( c=='\\' ) c = re_esc_char(p);
re_append(p, RE_OP_CC_RANGE, c);
}else{
re_append(p, RE_OP_CC_VALUE, c);
}
if( p->zIn[0]==']' ){ p->zIn++; break; }
}
if( c==0 ) return "unclosed '['";
p->aArg[iFirst] = p->nState - iFirst;
break;
}
case '\\': {
int specialOp = 0;
switch( p->zIn[0] ){
case 'b': specialOp = RE_OP_BOUNDARY; break;
case 'd': specialOp = RE_OP_DIGIT; break;
case 'D': specialOp = RE_OP_NOTDIGIT; break;
case 's': specialOp = RE_OP_SPACE; break;
case 'S': specialOp = RE_OP_NOTSPACE; break;
case 'w': specialOp = RE_OP_WORD; break;
case 'W': specialOp = RE_OP_NOTWORD; break;
}
if( specialOp ){
p->zIn++;
re_append(p, specialOp, 0);
}else{
c = re_esc_char(p);
re_append(p, RE_OP_MATCH, c);
}
break;
}
default: {
re_append(p, RE_OP_MATCH, c);
break;
}
}
iPrev = iStart;
}
return 0;
}
/* Free and reclaim all the memory used by a previously compiled
** regular expression. Applications should invoke this routine once
** for every call to re_compile() to avoid memory leaks.
*/
static void re_free(ReCompiled *pRe){
if( pRe ){
free(pRe->aOp);
free(pRe->aArg);
}
}
/*
** Compile a textual regular expression in zIn[] into a compiled regular
** expression suitable for us by re_exec() and return a pointer to the
** compiled regular expression in *ppRe. Return NULL on success or an
** error message if something goes wrong.
*/
static const char *re_compile(ReCompiled **ppRe, const char *zIn){
ReCompiled *pRe;
const char *zErr;
int i, j;
*ppRe = 0;
pRe = malloc( sizeof(*pRe) );
if( pRe==0 ){
return "out of memory";
}
memset(pRe, 0, sizeof(*pRe));
if( re_resize(pRe, 30) ){
re_free(pRe);
return "out of memory";
}
if( zIn[0]=='^' ){
zIn++;
}else{
re_append(pRe, RE_OP_ANYSTAR, 0);
}
pRe->zIn = (unsigned char*)zIn;
zErr = re_subcompile_re(pRe);
if( zErr ){
re_free(pRe);
return zErr;
}
if( pRe->zIn[0]=='$' && pRe->zIn[1]==0 ){
re_append(pRe, RE_OP_MATCH, RE_EOF);
re_append(pRe, RE_OP_ACCEPT, 0);
*ppRe = pRe;
}else if( pRe->zIn[0]==0 ){
re_append(pRe, RE_OP_ACCEPT, 0);
*ppRe = pRe;
}else{
re_free(pRe);
return "unrecognized character";
}
if( pRe->aOp[0]==RE_OP_ANYSTAR ){
for(j=0, i=1; j<sizeof(pRe->zInit)-2 && pRe->aOp[i]==RE_OP_MATCH; i++){
unsigned x = pRe->aArg[i];
if( x<=127 ){
pRe->zInit[j++] = x;
}else if( x<=0xfff ){
pRe->zInit[j++] = 0xc0 | (x>>6);
pRe->zInit[j++] = 0x80 | (x&0x3f);
}else if( x<=0xffff ){
pRe->zInit[j++] = 0xd0 | (x>>12);
pRe->zInit[j++] = 0x80 | ((x>>6)&0x3f);
pRe->zInit[j++] = 0x80 | ((x>>6)&0x3f);
}else{
break;
}
}
pRe->nInit = j;
}
return pRe->zErr;
}
/*
** Implementation of the regexp() SQL function. This function implements
** the build-in REGEXP operator. The first argument to the function is the
** pattern and the second argument is the string. So, the SQL statements:
**
** A REGEXP B
**
** is implemented as regexp(B,A).
*/
static void re_sql_func(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
ReCompiled *pRe; /* Compiled regular expression */
const char *zPattern; /* The regular expression */
const unsigned char *zStr;/* String being searched */
const char *zErr; /* Compile error message */
pRe = sqlite3_get_auxdata(context, 0);
if( pRe==0 ){
zPattern = (const char*)sqlite3_value_text(argv[0]);
if( zPattern==0 ) return;
zErr = re_compile(&pRe, zPattern);
if( zErr ){
sqlite3_result_error(context, zErr, -1);
return;
}
if( pRe==0 ){
sqlite3_result_error_nomem(context);
return;
}
sqlite3_set_auxdata(context, 0, pRe, (void(*)(void*))re_free);
}
zStr = (const unsigned char*)sqlite3_value_text(argv[1]);
if( zStr!=0 ){
sqlite3_result_int(context, re_exec(pRe, zStr));
}
}
/*
** Invoke this routine in order to install the REGEXP function in an
** SQLite database connection.
**
** Use:
**
** sqlite3_auto_extension(sqlite3_add_regexp_func);
**
** to cause this extension to be automatically loaded into each new
** database connection.
*/
int sqlite3_add_regexp_func(sqlite3 *db){
return sqlite3_create_function(db, "regexp", 2, SQLITE_UTF8, 0,
re_sql_func, 0, 0);
}
/***************************** Test Code ***********************************/
#ifdef SQLITE_TEST
#include <tcl.h>
extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
/* Implementation of the TCL command:
**
** sqlite3_add_regexp_func $DB
*/
static int tclSqlite3AddRegexpFunc(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
sqlite3 *db;
if( objc!=2 ){
Tcl_WrongNumArgs(interp, 1, objv, "DB");
return TCL_ERROR;
}
if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
sqlite3_add_regexp_func(db);
return TCL_OK;
}
/* Register the sqlite3_add_regexp_func TCL command with the TCL interpreter.
*/
int Sqlitetestregexp_Init(Tcl_Interp *interp){
Tcl_CreateObjCommand(interp, "sqlite3_add_regexp_func",
tclSqlite3AddRegexpFunc, 0, 0);
return TCL_OK;
}
#endif /* SQLITE_TEST */
/**************************** End Of Test Code *******************************/