From be782a0b0313d3b23473b6fd08e08ffea20156be Mon Sep 17 00:00:00 2001 From: daurnimator Date: Sun, 12 Nov 2017 15:28:26 +1100 Subject: src/defs.js: Avoid extra .slice operation --- src/defs.js | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'src') diff --git a/src/defs.js b/src/defs.js index e55e3dc..ad79c67 100644 --- a/src/defs.js +++ b/src/defs.js @@ -136,12 +136,16 @@ const is_luastring = function(s) { }; const to_jsstring = function(value, from, to) { - assert(is_luastring(value), "jsstring expect a array of bytes"); + assert(is_luastring(value), "jsstring expects an array of bytes"); - value = value.slice(from ? from : 0, to); + if (to === void 0) { + to = value.length; + } else { + to = Math.min(value.length, to); + } let str = ""; - for (let i = 0; i < value.length;) { + for (let i = (from!==void 0?from:0); i < to;) { let u; let u0 = value[i++]; if (u0 < 0x80) { @@ -151,18 +155,18 @@ const to_jsstring = function(value, from, to) { throw RangeError("cannot convert invalid utf8 to javascript string"); } else if (u0 <= 0xDF) { /* two byte sequence */ - if (i >= value.length) throw RangeError("cannot convert invalid utf8 to javascript string"); + if (i >= to) throw RangeError("cannot convert invalid utf8 to javascript string"); let u1 = value[i++]; u = ((u0 & 0x1F) << 6) + (u1 & 0x3F); } else if (u0 <= 0xEF) { /* three byte sequence */ - if (i+1 >= value.length) throw RangeError("cannot convert invalid utf8 to javascript string"); + if (i+1 >= to) throw RangeError("cannot convert invalid utf8 to javascript string"); let u1 = value[i++]; let u2 = value[i++]; u = ((u0 & 0x0F) << 12) + ((u1 & 0x3F) << 6) + (u2 & 0x3F); } else { /* four byte sequence */ - if (i+2 >= value.length) throw RangeError("cannot convert invalid utf8 to javascript string"); + if (i+2 >= to) throw RangeError("cannot convert invalid utf8 to javascript string"); let u1 = value[i++]; let u2 = value[i++]; let u3 = value[i++]; -- cgit v1.2.3-70-g09d2