string.gsub

2 files changed, 60 insertions, 0 deletions

diff --git a/src/lapi.js b/src/lapi.js
index a884a97..6840ef9 100644
--- a/src/lapi.js
+++ b/src/lapi.js
@@ -428,6 +428,14 @@ const lua_createtable = function(L, narray, nrec) {
     assert(L.top <= L.ci.top, "stack overflow");
 };
 
+const lua_newuserdata = function(L, u) {
+    L.stack[L.top++] = new lobject.TValue(CT.LUA_TUSERDATA, u);
+
+    assert(L.top <= L.ci.top, "stack overflow");
+
+    return L.stack[L.top - 1].value;
+};
+
 const aux_upvalue = function(fi, n) {
     switch(fi.ttype()) {
         case CT.LUAT_TCCL: {  /* C closure */
@@ -578,6 +586,16 @@ const lua_tonumber = function(L, idx) {
     return lvm.tonumber(index2addr(L, idx));
 };
 
+const lua_touserdata = function(L, idx) {
+    let o = index2addr(L, idx);
+    switch (o.ttnov()) {
+        case CT.LUA_TUSERDATA:
+        case CT.LUA_TLIGHTUSERDATA:
+            return o.value;
+        default: return null;
+    }
+};
+
 const lua_tothread = function(L, idx) {
     let o = index2addr(L, idx);
     return o.ttisthread() ? o.value : null;
@@ -879,6 +897,7 @@ module.exports.lua_istable         = lua_istable;
 module.exports.lua_len             = lua_len;
 module.exports.lua_load            = lua_load;
 module.exports.lua_newtable        = lua_newtable;
+module.exports.lua_newuserdata     = lua_newuserdata;
 module.exports.lua_next            = lua_next;
 module.exports.lua_pcall           = lua_pcall;
 module.exports.lua_pcallk          = lua_pcallk;
@@ -924,6 +943,7 @@ module.exports.lua_tonumber        = lua_tonumber;
 module.exports.lua_topointer       = lua_topointer;
 module.exports.lua_tostring        = lua_tostring;
 module.exports.lua_tothread        = lua_tothread;
+module.exports.lua_touserdata      = lua_touserdata;
 module.exports.lua_type            = lua_type;
 module.exports.lua_typename        = lua_typename;
 module.exports.lua_version         = lua_version;
diff --git a/src/lstrlib.js b/src/lstrlib.js
index cedb403..9caa3cc 100644
--- a/src/lstrlib.js
+++ b/src/lstrlib.js
@@ -1221,12 +1221,52 @@ const str_match = function(L) {
     return str_find_aux(L, 0);
 };
 
+/* state for 'gmatch' */
+class GMatchState {
+    constructor() {
+        this.src = NaN;  /* current position */
+        this.p = NaN;  /* pattern */
+        this.lastmatch = NaN;  /* end of last match */
+        this.ms = new MatchState();  /* match state */
+    }
+}
+
+const gmatch_aux = function(L) {
+    let gm = lapi.lua_touserdata(L, lua.lua_upvalueindex(3));
+    gm.ms.L = L;
+    for (let src = 0; src < gm.ms.src_end; src++) {
+        reprepstate(gm.ms);
+        let e;
+        if ((e = match(gm.ms, src, gm.p)) !== null && e !== gm.lastmatch) {
+            gm.src = gm.lastmatch = e;
+            return push_captures(gm.ms, src, e);
+        }
+    }
+    return 0;  /* not found */
+};
+
+const str_gmatch = function(L) {
+    let s = lauxlib.luaL_checkstring(L, 1);
+    let p = lauxlib.luaL_checkstring(L, 2);
+    let ls = s.length;
+    let lp = p.length;
+    lapi.lua_settop(L, 2);  /* keep them on closure to avoid being collected */
+    let gm = lapi.lua_newuserdata(L, new GMatchState());
+    prepstate(gm.ms, L, s, ls, p, lp);
+    gm.src = s;
+    gm.p = p;
+    gm.lastmatch = null;
+    lapi.lua_pushcclosure(L, gmatch_aux, 3);
+    return 1;
+};
+
 const strlib = {
     "byte":     str_byte,
     "char":     str_char,
     "dump":     str_dump,
     "find":     str_find,
     "format":   str_format,
+    "gmatch":   str_gmatch,
     "len":      str_len,
     "lower":    str_lower,
     "match":    str_match,