Move jsstring() from lobject.js to defs.js; export from lua.js

1 files changed, 45 insertions, 0 deletions

diff --git a/src/defs.js b/src/defs.js
index fd8038a..34316e9 100644
--- a/src/defs.js
+++ b/src/defs.js
@@ -134,6 +134,50 @@ class lua_Debug {
 
 }
 
+const to_jsstring = function(value, from, to) {
+    assert(Array.isArray(value), "jsstring expect a array of bytes");
+
+    let u0, u1, u2, u3, u4, u5;
+    let idx = 0;
+    value = value.slice(from ? from : 0, to);
+
+    var str = '';
+    while (1) {
+        // For UTF8 byte structure, see http://en.wikipedia.org/wiki/UTF-8#Description and https://www.ietf.org/rfc/rfc2279.txt and https://tools.ietf.org/html/rfc3629
+        u0 = value[idx++];
+        if (u0 === 0) { str += "\0"; continue; } // Lua string embed '\0'
+        if (!u0) return str;
+        if (!(u0 & 0x80)) { str += String.fromCharCode(u0); continue; }
+        u1 = value[idx++] & 63;
+        if ((u0 & 0xE0) == 0xC0) { str += String.fromCharCode(((u0 & 31) << 6) | u1); continue; }
+        u2 = value[idx++] & 63;
+        if ((u0 & 0xF0) == 0xE0) {
+            u0 = ((u0 & 15) << 12) | (u1 << 6) | u2;
+        } else {
+            u3 = value[idx++] & 63;
+            if ((u0 & 0xF8) == 0xF0) {
+                u0 = ((u0 & 7) << 18) | (u1 << 12) | (u2 << 6) | u3;
+            } else {
+                u4 = value[idx++] & 63;
+                if ((u0 & 0xFC) == 0xF8) {
+                    u0 = ((u0 & 3) << 24) | (u1 << 18) | (u2 << 12) | (u3 << 6) | u4;
+                } else {
+                    u5 = value[idx++] & 63;
+                    u0 = ((u0 & 1) << 30) | (u1 << 24) | (u2 << 18) | (u3 << 12) | (u4 << 6) | u5;
+                }
+            }
+        }
+        if (u0 < 0x10000) {
+            str += String.fromCharCode(u0);
+        } else {
+            var ch = u0 - 0x10000;
+            str += String.fromCharCode(0xD800 | (ch >> 10), 0xDC00 | (ch & 0x3FF));
+        }
+    }
+
+    return str;
+};
+
 const to_luastring_cache = {};
 
 const to_luastring = function(str, cache, maxBytesToWrite) {
@@ -277,4 +321,5 @@ module.exports.constant_types          = constant_types;
 module.exports.lua_Debug               = lua_Debug;
 module.exports.lua_upvalueindex        = lua_upvalueindex;
 module.exports.thread_status           = thread_status;
+module.exports.to_jsstring             = to_jsstring;
 module.exports.to_luastring            = to_luastring;