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/*
** $Id: lpcap.c,v 1.4 2013/03/21 20:25:12 roberto Exp $
** Copyright 2007, Lua.org & PUC-Rio (see 'lpeg.html' for license)
*/
#include "lua.h"
#include "lauxlib.h"
#include "lpcap.h"
#include "lptypes.h"
#define captype(cap) ((cap)->kind)
#define isclosecap(cap) (captype(cap) == Cclose)
#define closeaddr(c) ((c)->s + (c)->siz - 1)
#define isfullcap(cap) ((cap)->siz != 0)
#define getfromktable(cs,v) lua_rawgeti((cs)->L, ktableidx((cs)->ptop), v)
#define pushluaval(cs) getfromktable(cs, (cs)->cap->idx)
/*
** Put at the cache for Lua values the value indexed by 'v' in ktable
** of the running pattern (if it is not there yet); returns its index.
*/
static int updatecache (CapState *cs, int v) {
int idx = cs->ptop + 1; /* stack index of cache for Lua values */
if (v != cs->valuecached) { /* not there? */
getfromktable(cs, v); /* get value from 'ktable' */
lua_replace(cs->L, idx); /* put it at reserved stack position */
cs->valuecached = v; /* keep track of what is there */
}
return idx;
}
static int pushcapture (CapState *cs);
/*
** Goes back in a list of captures looking for an open capture
** corresponding to a close
*/
static Capture *findopen (Capture *cap) {
int n = 0; /* number of closes waiting an open */
for (;;) {
cap--;
if (isclosecap(cap)) n++; /* one more open to skip */
else if (!isfullcap(cap))
if (n-- == 0) return cap;
}
}
/*
** Go to the next capture
*/
static void nextcap (CapState *cs) {
Capture *cap = cs->cap;
if (!isfullcap(cap)) { /* not a single capture? */
int n = 0; /* number of opens waiting a close */
for (;;) { /* look for corresponding close */
cap++;
if (isclosecap(cap)) {
if (n-- == 0) break;
}
else if (!isfullcap(cap)) n++;
}
}
cs->cap = cap + 1; /* + 1 to skip last close (or entire single capture) */
}
/*
** Push on the Lua stack all values generated by nested captures inside
** the current capture. Returns number of values pushed. 'addextra'
** makes it push the entire match after all captured values. The
** entire match is pushed also if there are no other nested values,
** so the function never returns zero.
*/
static int pushnestedvalues (CapState *cs, int addextra) {
Capture *co = cs->cap;
if (isfullcap(cs->cap++)) { /* no nested captures? */
lua_pushlstring(cs->L, co->s, co->siz - 1); /* push whole match */
return 1; /* that is it */
}
else {
int n = 0;
while (!isclosecap(cs->cap)) /* repeat for all nested patterns */
n += pushcapture(cs);
if (addextra || n == 0) { /* need extra? */
lua_pushlstring(cs->L, co->s, cs->cap->s - co->s); /* push whole match */
n++;
}
cs->cap++; /* skip close entry */
return n;
}
}
/*
** Push only the first value generated by nested captures
*/
static void pushonenestedvalue (CapState *cs) {
int n = pushnestedvalues(cs, 0);
if (n > 1)
lua_pop(cs->L, n - 1); /* pop extra values */
}
/*
** Try to find a named group capture with the name given at the top of
** the stack; goes backward from 'cap'.
*/
static Capture *findback (CapState *cs, Capture *cap) {
lua_State *L = cs->L;
while (cap-- > cs->ocap) { /* repeat until end of list */
if (isclosecap(cap))
cap = findopen(cap); /* skip nested captures */
else if (!isfullcap(cap))
continue; /* opening an enclosing capture: skip and get previous */
if (captype(cap) == Cgroup) {
getfromktable(cs, cap->idx); /* get group name */
if (lua_equal(L, -2, -1)) { /* right group? */
lua_pop(L, 2); /* remove reference name and group name */
return cap;
}
else lua_pop(L, 1); /* remove group name */
}
}
luaL_error(L, "back reference '%s' not found", lua_tostring(L, -1));
return NULL; /* to avoid warnings */
}
/*
** Back-reference capture. Return number of values pushed.
*/
static int backrefcap (CapState *cs) {
int n;
Capture *curr = cs->cap;
pushluaval(cs); /* reference name */
cs->cap = findback(cs, curr); /* find corresponding group */
n = pushnestedvalues(cs, 0); /* push group's values */
cs->cap = curr + 1;
return n;
}
/*
** Table capture: creates a new table and populates it with nested
** captures.
*/
static int tablecap (CapState *cs) {
lua_State *L = cs->L;
int n = 0;
lua_newtable(L);
if (isfullcap(cs->cap++))
return 1; /* table is empty */
while (!isclosecap(cs->cap)) {
if (captype(cs->cap) == Cgroup && cs->cap->idx != 0) { /* named group? */
pushluaval(cs); /* push group name */
pushonenestedvalue(cs);
lua_settable(L, -3);
}
else { /* not a named group */
int i;
int k = pushcapture(cs);
for (i = k; i > 0; i--) /* store all values into table */
lua_rawseti(L, -(i + 1), n + i);
n += k;
}
}
cs->cap++; /* skip close entry */
return 1; /* number of values pushed (only the table) */
}
/*
** Table-query capture
*/
static int querycap (CapState *cs) {
int idx = cs->cap->idx;
pushonenestedvalue(cs); /* get nested capture */
lua_gettable(cs->L, updatecache(cs, idx)); /* query cap. value at table */
if (!lua_isnil(cs->L, -1))
return 1;
else { /* no value */
lua_pop(cs->L, 1); /* remove nil */
return 0;
}
}
/*
** Fold capture
*/
static int foldcap (CapState *cs) {
int n;
lua_State *L = cs->L;
int idx = cs->cap->idx;
if (isfullcap(cs->cap++) || /* no nested captures? */
isclosecap(cs->cap) || /* no nested captures (large subject)? */
(n = pushcapture(cs)) == 0) /* nested captures with no values? */
return luaL_error(L, "no initial value for fold capture");
if (n > 1)
lua_pop(L, n - 1); /* leave only one result for accumulator */
while (!isclosecap(cs->cap)) {
lua_pushvalue(L, updatecache(cs, idx)); /* get folding function */
lua_insert(L, -2); /* put it before accumulator */
n = pushcapture(cs); /* get next capture's values */
lua_call(L, n + 1, 1); /* call folding function */
}
cs->cap++; /* skip close entry */
return 1; /* only accumulator left on the stack */
}
/*
** Function capture
*/
static int functioncap (CapState *cs) {
int n;
int top = lua_gettop(cs->L);
pushluaval(cs); /* push function */
n = pushnestedvalues(cs, 0); /* push nested captures */
lua_call(cs->L, n, LUA_MULTRET); /* call function */
return lua_gettop(cs->L) - top; /* return function's results */
}
/*
** Select capture
*/
static int numcap (CapState *cs) {
int idx = cs->cap->idx; /* value to select */
if (idx == 0) { /* no values? */
nextcap(cs); /* skip entire capture */
return 0; /* no value produced */
}
else {
int n = pushnestedvalues(cs, 0);
if (n < idx) /* invalid index? */
return luaL_error(cs->L, "no capture '%d'", idx);
else {
lua_pushvalue(cs->L, -(n - idx + 1)); /* get selected capture */
lua_replace(cs->L, -(n + 1)); /* put it in place of 1st capture */
lua_pop(cs->L, n - 1); /* remove other captures */
return 1;
}
}
}
/*
** Return the stack index of the first runtime capture in the given
** list of captures (or zero if no runtime captures)
*/
int finddyncap (Capture *cap, Capture *last) {
for (; cap < last; cap++) {
if (cap->kind == Cruntime)
return cap->idx; /* stack position of first capture */
}
return 0; /* no dynamic captures in this segment */
}
/*
** Calls a runtime capture. Returns number of captures removed by
** the call, including the initial Cgroup. (Captures to be added are
** on the Lua stack.)
*/
int runtimecap (CapState *cs, Capture *close, const char *s, int *rem) {
int n, id;
lua_State *L = cs->L;
int otop = lua_gettop(L);
Capture *open = findopen(close);
assert(captype(open) == Cgroup);
id = finddyncap(open, close); /* get first dynamic capture argument */
close->kind = Cclose; /* closes the group */
close->s = s;
cs->cap = open; cs->valuecached = 0; /* prepare capture state */
luaL_checkstack(L, 4, "too many runtime captures");
pushluaval(cs); /* push function to be called */
lua_pushvalue(L, SUBJIDX); /* push original subject */
lua_pushinteger(L, s - cs->s + 1); /* push current position */
n = pushnestedvalues(cs, 0); /* push nested captures */
lua_call(L, n + 2, LUA_MULTRET); /* call dynamic function */
if (id > 0) { /* are there old dynamic captures to be removed? */
int i;
for (i = id; i <= otop; i++)
lua_remove(L, id); /* remove old dynamic captures */
*rem = otop - id + 1; /* total number of dynamic captures removed */
}
else
*rem = 0; /* no dynamic captures removed */
return close - open; /* number of captures of all kinds removed */
}
/*
** Auxiliary structure for substitution and string captures: keep
** information about nested captures for future use, avoiding to push
** string results into Lua
*/
typedef struct StrAux {
int isstring; /* whether capture is a string */
union {
Capture *cp; /* if not a string, respective capture */
struct { /* if it is a string... */
const char *s; /* ... starts here */
const char *e; /* ... ends here */
} s;
} u;
} StrAux;
#define MAXSTRCAPS 10
/*
** Collect values from current capture into array 'cps'. Current
** capture must be Cstring (first call) or Csimple (recursive calls).
** (In first call, fills %0 with whole match for Cstring.)
** Returns number of elements in the array that were filled.
*/
static int getstrcaps (CapState *cs, StrAux *cps, int n) {
int k = n++;
cps[k].isstring = 1; /* get string value */
cps[k].u.s.s = cs->cap->s; /* starts here */
if (!isfullcap(cs->cap++)) { /* nested captures? */
while (!isclosecap(cs->cap)) { /* traverse them */
if (n >= MAXSTRCAPS) /* too many captures? */
nextcap(cs); /* skip extra captures (will not need them) */
else if (captype(cs->cap) == Csimple) /* string? */
n = getstrcaps(cs, cps, n); /* put info. into array */
else {
cps[n].isstring = 0; /* not a string */
cps[n].u.cp = cs->cap; /* keep original capture */
nextcap(cs);
n++;
}
}
cs->cap++; /* skip close */
}
cps[k].u.s.e = closeaddr(cs->cap - 1); /* ends here */
return n;
}
/*
** add next capture value (which should be a string) to buffer 'b'
*/
static int addonestring (luaL_Buffer *b, CapState *cs, const char *what);
/*
** String capture: add result to buffer 'b' (instead of pushing
** it into the stack)
*/
static void stringcap (luaL_Buffer *b, CapState *cs) {
StrAux cps[MAXSTRCAPS];
int n;
size_t len, i;
const char *fmt; /* format string */
fmt = lua_tolstring(cs->L, updatecache(cs, cs->cap->idx), &len);
n = getstrcaps(cs, cps, 0) - 1; /* collect nested captures */
for (i = 0; i < len; i++) { /* traverse them */
if (fmt[i] != '%') /* not an escape? */
luaL_addchar(b, fmt[i]); /* add it to buffer */
else if (fmt[++i] < '0' || fmt[i] > '9') /* not followed by a digit? */
luaL_addchar(b, fmt[i]); /* add to buffer */
else {
int l = fmt[i] - '0'; /* capture index */
if (l > n)
luaL_error(cs->L, "invalid capture index (%d)", l);
else if (cps[l].isstring)
luaL_addlstring(b, cps[l].u.s.s, cps[l].u.s.e - cps[l].u.s.s);
else {
Capture *curr = cs->cap;
cs->cap = cps[l].u.cp; /* go back to evaluate that nested capture */
if (!addonestring(b, cs, "capture"))
luaL_error(cs->L, "no values in capture index %d", l);
cs->cap = curr; /* continue from where it stopped */
}
}
}
}
/*
** Substitution capture: add result to buffer 'b'
*/
static void substcap (luaL_Buffer *b, CapState *cs) {
const char *curr = cs->cap->s;
if (isfullcap(cs->cap)) /* no nested captures? */
luaL_addlstring(b, curr, cs->cap->siz - 1); /* keep original text */
else {
cs->cap++; /* skip open entry */
while (!isclosecap(cs->cap)) { /* traverse nested captures */
const char *next = cs->cap->s;
luaL_addlstring(b, curr, next - curr); /* add text up to capture */
if (addonestring(b, cs, "replacement"))
curr = closeaddr(cs->cap - 1); /* continue after match */
else /* no capture value */
curr = next; /* keep original text in final result */
}
luaL_addlstring(b, curr, cs->cap->s - curr); /* add last piece of text */
}
cs->cap++; /* go to next capture */
}
/*
** Evaluates a capture and adds its first value to buffer 'b'; returns
** whether there was a value
*/
static int addonestring (luaL_Buffer *b, CapState *cs, const char *what) {
switch (captype(cs->cap)) {
case Cstring:
stringcap(b, cs); /* add capture directly to buffer */
return 1;
case Csubst:
substcap(b, cs); /* add capture directly to buffer */
return 1;
default: {
lua_State *L = cs->L;
int n = pushcapture(cs);
if (n > 0) {
if (n > 1) lua_pop(L, n - 1); /* only one result */
if (!lua_isstring(L, -1))
luaL_error(L, "invalid %s value (a %s)", what, luaL_typename(L, -1));
luaL_addvalue(b);
}
return n;
}
}
}
/*
** Push all values of the current capture into the stack; returns
** number of values pushed
*/
static int pushcapture (CapState *cs) {
lua_State *L = cs->L;
luaL_checkstack(L, 4, "too many captures");
switch (captype(cs->cap)) {
case Cposition: {
lua_pushinteger(L, cs->cap->s - cs->s + 1);
cs->cap++;
return 1;
}
case Cconst: {
pushluaval(cs);
cs->cap++;
return 1;
}
case Carg: {
int arg = (cs->cap++)->idx;
if (arg + FIXEDARGS > cs->ptop)
return luaL_error(L, "reference to absent argument #%d", arg);
lua_pushvalue(L, arg + FIXEDARGS);
return 1;
}
case Csimple: {
int k = pushnestedvalues(cs, 1);
lua_insert(L, -k); /* make whole match be first result */
return k;
}
case Cruntime: {
lua_pushvalue(L, (cs->cap++)->idx); /* value is in the stack */
return 1;
}
case Cstring: {
luaL_Buffer b;
luaL_buffinit(L, &b);
stringcap(&b, cs);
luaL_pushresult(&b);
return 1;
}
case Csubst: {
luaL_Buffer b;
luaL_buffinit(L, &b);
substcap(&b, cs);
luaL_pushresult(&b);
return 1;
}
case Cgroup: {
if (cs->cap->idx == 0) /* anonymous group? */
return pushnestedvalues(cs, 0); /* add all nested values */
else { /* named group: add no values */
nextcap(cs); /* skip capture */
return 0;
}
}
case Cbackref: return backrefcap(cs);
case Ctable: return tablecap(cs);
case Cfunction: return functioncap(cs);
case Cnum: return numcap(cs);
case Cquery: return querycap(cs);
case Cfold: return foldcap(cs);
default: assert(0); return 0;
}
}
/*
** Prepare a CapState structure and traverse the entire list of
** captures in the stack pushing its results. 's' is the subject
** string, 'r' is the final position of the match, and 'ptop'
** the index in the stack where some useful values were pushed.
** Returns the number of results pushed. (If the list produces no
** results, push the final position of the match.)
*/
int getcaptures (lua_State *L, const char *s, const char *r, int ptop) {
Capture *capture = (Capture *)lua_touserdata(L, caplistidx(ptop));
int n = 0;
if (!isclosecap(capture)) { /* is there any capture? */
CapState cs;
cs.ocap = cs.cap = capture; cs.L = L;
cs.s = s; cs.valuecached = 0; cs.ptop = ptop;
do { /* collect their values */
n += pushcapture(&cs);
} while (!isclosecap(cs.cap));
}
if (n == 0) { /* no capture values? */
lua_pushinteger(L, r - s + 1); /* return only end position */
n = 1;
}
return n;
}
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