1 files changed, 364 insertions, 0 deletions

diff --git a/lpvm.c b/lpvm.c
new file mode 100644
index 0000000..05a5f68
--- /dev/null
+++ b/lpvm.c
@@ -0,0 +1,364 @@
+/*
+** $Id: lpvm.c,v 1.9 2016/06/03 20:11:18 roberto Exp $
+** Copyright 2007, Lua.org & PUC-Rio  (see 'lpeg.html' for license)
+*/
+
+#include <limits.h>
+#include <string.h>
+
+
+#include "lua.h"
+#include "lauxlib.h"
+
+#include "lpcap.h"
+#include "lptypes.h"
+#include "lpvm.h"
+#include "lpprint.h"
+
+
+/* initial size for call/backtrack stack */
+#if !defined(INITBACK)
+#define INITBACK        MAXBACK
+#endif
+
+
+#define getoffset(p)    (((p) + 1)->offset)
+
+static const Instruction giveup = {{IGiveup, 0, 0}};
+
+
+/*
+** {======================================================
+** Virtual Machine
+** =======================================================
+*/
+
+
+typedef struct Stack {
+  const char *s;  /* saved position (or NULL for calls) */
+  const Instruction *p;  /* next instruction */
+  int caplevel;
+} Stack;
+
+
+#define getstackbase(L, ptop)   ((Stack *)lua_touserdata(L, stackidx(ptop)))
+
+
+/*
+** Make the size of the array of captures 'cap' twice as large as needed
+** (which is 'captop'). ('n' is the number of new elements.)
+*/
+static Capture *doublecap (lua_State *L, Capture *cap, int captop,
+                                         int n, int ptop) {
+  Capture *newc;
+  if (captop >= INT_MAX/((int)sizeof(Capture) * 2))
+    luaL_error(L, "too many captures");
+  newc = (Capture *)lua_newuserdata(L, captop * 2 * sizeof(Capture));
+  memcpy(newc, cap, (captop - n) * sizeof(Capture));
+  lua_replace(L, caplistidx(ptop));
+  return newc;
+}
+
+
+/*
+** Double the size of the stack
+*/
+static Stack *doublestack (lua_State *L, Stack **stacklimit, int ptop) {
+  Stack *stack = getstackbase(L, ptop);
+  Stack *newstack;
+  int n = *stacklimit - stack;  /* current stack size */
+  int max, newn;
+  lua_getfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);
+  max = lua_tointeger(L, -1);  /* maximum allowed size */
+  lua_pop(L, 1);
+  if (n >= max)  /* already at maximum size? */
+    luaL_error(L, "backtrack stack overflow (current limit is %d)", max);
+  newn = 2 * n;  /* new size */
+  if (newn > max) newn = max;
+  newstack = (Stack *)lua_newuserdata(L, newn * sizeof(Stack));
+  memcpy(newstack, stack, n * sizeof(Stack));
+  lua_replace(L, stackidx(ptop));
+  *stacklimit = newstack + newn;
+  return newstack + n;  /* return next position */
+}
+
+
+/*
+** Interpret the result of a dynamic capture: false -> fail;
+** true -> keep current position; number -> next position.
+** Return new subject position. 'fr' is stack index where
+** is the result; 'curr' is current subject position; 'limit'
+** is subject's size.
+*/
+static int resdyncaptures (lua_State *L, int fr, int curr, int limit) {
+  lua_Integer res;
+  if (!lua_toboolean(L, fr)) {  /* false value? */
+    lua_settop(L, fr - 1);  /* remove results */
+    return -1;  /* and fail */
+  }
+  else if (lua_isboolean(L, fr))  /* true? */
+    res = curr;  /* keep current position */
+  else {
+    res = lua_tointeger(L, fr) - 1;  /* new position */
+    if (res < curr || res > limit)
+      luaL_error(L, "invalid position returned by match-time capture");
+  }
+  lua_remove(L, fr);  /* remove first result (offset) */
+  return res;
+}
+
+
+/*
+** Add capture values returned by a dynamic capture to the capture list
+** 'base', nested inside a group capture. 'fd' indexes the first capture
+** value, 'n' is the number of values (at least 1).
+*/
+static void adddyncaptures (const char *s, Capture *base, int n, int fd) {
+  int i;
+  base[0].kind = Cgroup;  /* create group capture */
+  base[0].siz = 0;
+  base[0].idx = 0;  /* make it an anonymous group */
+  for (i = 1; i <= n; i++) {  /* add runtime captures */
+    base[i].kind = Cruntime;
+    base[i].siz = 1;  /* mark it as closed */
+    base[i].idx = fd + i - 1;  /* stack index of capture value */
+    base[i].s = s;
+  }
+  base[i].kind = Cclose;  /* close group */
+  base[i].siz = 1;
+  base[i].s = s;
+}
+
+
+/*
+** Remove dynamic captures from the Lua stack (called in case of failure)
+*/
+static int removedyncap (lua_State *L, Capture *capture,
+                         int level, int last) {
+  int id = finddyncap(capture + level, capture + last);  /* index of 1st cap. */
+  int top = lua_gettop(L);
+  if (id == 0) return 0;  /* no dynamic captures? */
+  lua_settop(L, id - 1);  /* remove captures */
+  return top - id + 1;  /* number of values removed */
+}
+
+
+/*
+** Opcode interpreter
+*/
+const char *match (lua_State *L, const char *o, const char *s, const char *e,
+                   Instruction *op, Capture *capture, int ptop) {
+  Stack stackbase[INITBACK];
+  Stack *stacklimit = stackbase + INITBACK;
+  Stack *stack = stackbase;  /* point to first empty slot in stack */
+  int capsize = INITCAPSIZE;
+  int captop = 0;  /* point to first empty slot in captures */
+  int ndyncap = 0;  /* number of dynamic captures (in Lua stack) */
+  const Instruction *p = op;  /* current instruction */
+  stack->p = &giveup; stack->s = s; stack->caplevel = 0; stack++;
+  lua_pushlightuserdata(L, stackbase);
+  for (;;) {
+#if defined(DEBUG)
+      printf("-------------------------------------\n");
+      printcaplist(capture, capture + captop);
+      printf("s: |%s| stck:%d, dyncaps:%d, caps:%d  ",
+             s, (int)(stack - getstackbase(L, ptop)), ndyncap, captop);
+      printinst(op, p);
+#endif
+    assert(stackidx(ptop) + ndyncap == lua_gettop(L) && ndyncap <= captop);
+    switch ((Opcode)p->i.code) {
+      case IEnd: {
+        assert(stack == getstackbase(L, ptop) + 1);
+        capture[captop].kind = Cclose;
+        capture[captop].s = NULL;
+        return s;
+      }
+      case IGiveup: {
+        assert(stack == getstackbase(L, ptop));
+        return NULL;
+      }
+      case IRet: {
+        assert(stack > getstackbase(L, ptop) && (stack - 1)->s == NULL);
+        p = (--stack)->p;
+        continue;
+      }
+      case IAny: {
+        if (s < e) { p++; s++; }
+        else goto fail;
+        continue;
+      }
+      case ITestAny: {
+        if (s < e) p += 2;
+        else p += getoffset(p);
+        continue;
+      }
+      case IChar: {
+        if ((byte)*s == p->i.aux && s < e) { p++; s++; }
+        else goto fail;
+        continue;
+      }
+      case ITestChar: {
+        if ((byte)*s == p->i.aux && s < e) p += 2;
+        else p += getoffset(p);
+        continue;
+      }
+      case ISet: {
+        int c = (byte)*s;
+        if (testchar((p+1)->buff, c) && s < e)
+          { p += CHARSETINSTSIZE; s++; }
+        else goto fail;
+        continue;
+      }
+      case ITestSet: {
+        int c = (byte)*s;
+        if (testchar((p + 2)->buff, c) && s < e)
+          p += 1 + CHARSETINSTSIZE;
+        else p += getoffset(p);
+        continue;
+      }
+      case IBehind: {
+        int n = p->i.aux;
+        if (n > s - o) goto fail;
+        s -= n; p++;
+        continue;
+      }
+      case ISpan: {
+        for (; s < e; s++) {
+          int c = (byte)*s;
+          if (!testchar((p+1)->buff, c)) break;
+        }
+        p += CHARSETINSTSIZE;
+        continue;
+      }
+      case IJmp: {
+        p += getoffset(p);
+        continue;
+      }
+      case IChoice: {
+        if (stack == stacklimit)
+          stack = doublestack(L, &stacklimit, ptop);
+        stack->p = p + getoffset(p);
+        stack->s = s;
+        stack->caplevel = captop;
+        stack++;
+        p += 2;
+        continue;
+      }
+      case ICall: {
+        if (stack == stacklimit)
+          stack = doublestack(L, &stacklimit, ptop);
+        stack->s = NULL;
+        stack->p = p + 2;  /* save return address */
+        stack++;
+        p += getoffset(p);
+        continue;
+      }
+      case ICommit: {
+        assert(stack > getstackbase(L, ptop) && (stack - 1)->s != NULL);
+        stack--;
+        p += getoffset(p);
+        continue;
+      }
+      case IPartialCommit: {
+        assert(stack > getstackbase(L, ptop) && (stack - 1)->s != NULL);
+        (stack - 1)->s = s;
+        (stack - 1)->caplevel = captop;
+        p += getoffset(p);
+        continue;
+      }
+      case IBackCommit: {
+        assert(stack > getstackbase(L, ptop) && (stack - 1)->s != NULL);
+        s = (--stack)->s;
+        captop = stack->caplevel;
+        p += getoffset(p);
+        continue;
+      }
+      case IFailTwice:
+        assert(stack > getstackbase(L, ptop));
+        stack--;
+        /* go through */
+      case IFail:
+      fail: { /* pattern failed: try to backtrack */
+        do {  /* remove pending calls */
+          assert(stack > getstackbase(L, ptop));
+          s = (--stack)->s;
+        } while (s == NULL);
+        if (ndyncap > 0)  /* is there matchtime captures? */
+          ndyncap -= removedyncap(L, capture, stack->caplevel, captop);
+        captop = stack->caplevel;
+        p = stack->p;
+#if defined(DEBUG)
+        printf("**FAIL**\n");
+#endif
+        continue;
+      }
+      case ICloseRunTime: {
+        CapState cs;
+        int rem, res, n;
+        int fr = lua_gettop(L) + 1;  /* stack index of first result */
+        cs.s = o; cs.L = L; cs.ocap = capture; cs.ptop = ptop;
+        n = runtimecap(&cs, capture + captop, s, &rem);  /* call function */
+        captop -= n;  /* remove nested captures */
+        ndyncap -= rem;  /* update number of dynamic captures */
+        fr -= rem;  /* 'rem' items were popped from Lua stack */
+        res = resdyncaptures(L, fr, s - o, e - o);  /* get result */
+        if (res == -1)  /* fail? */
+          goto fail;
+        s = o + res;  /* else update current position */
+        n = lua_gettop(L) - fr + 1;  /* number of new captures */
+        ndyncap += n;  /* update number of dynamic captures */
+        if (n > 0) {  /* any new capture? */
+          if (fr + n >= SHRT_MAX)
+            luaL_error(L, "too many results in match-time capture");
+          if ((captop += n + 2) >= capsize) {
+            capture = doublecap(L, capture, captop, n + 2, ptop);
+            capsize = 2 * captop;
+          }
+          /* add new captures to 'capture' list */
+          adddyncaptures(s, capture + captop - n - 2, n, fr); 
+        }
+        p++;
+        continue;
+      }
+      case ICloseCapture: {
+        const char *s1 = s;
+        assert(captop > 0);
+        /* if possible, turn capture into a full capture */
+        if (capture[captop - 1].siz == 0 &&
+            s1 - capture[captop - 1].s < UCHAR_MAX) {
+          capture[captop - 1].siz = s1 - capture[captop - 1].s + 1;
+          p++;
+          continue;
+        }
+        else {
+          capture[captop].siz = 1;  /* mark entry as closed */
+          capture[captop].s = s;
+          goto pushcapture;
+        }
+      }
+      case IOpenCapture:
+        capture[captop].siz = 0;  /* mark entry as open */
+        capture[captop].s = s;
+        goto pushcapture;
+      case IFullCapture:
+        capture[captop].siz = getoff(p) + 1;  /* save capture size */
+        capture[captop].s = s - getoff(p);
+        /* goto pushcapture; */
+      pushcapture: {
+        capture[captop].idx = p->i.key;
+        capture[captop].kind = getkind(p);
+        if (++captop >= capsize) {
+          capture = doublecap(L, capture, captop, 0, ptop);
+          capsize = 2 * captop;
+        }
+        p++;
+        continue;
+      }
+      default: assert(0); return NULL;
+    }
+  }
+}
+
+/* }====================================================== */
+
+