From ba6e29d6fd8df2434cb372b94c7aaccb68bc272f Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Mon, 1 Feb 2021 09:20:13 +0000
Subject: introduce `templates` (#4603)

---
 lib/parse.js | 95 ++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 54 insertions(+), 41 deletions(-)

(limited to 'lib/parse.js')

diff --git a/lib/parse.js b/lib/parse.js
index 5b77d675..bc72550f 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -145,6 +145,43 @@ function is_identifier_string(str) {
     return /^[a-z_$][a-z0-9_$]*$/i.test(str);
 }
 
+function decode_escape_sequence(seq) {
+    switch (seq[0]) {
+      case "b": return "\b";
+      case "f": return "\f";
+      case "n": return "\n";
+      case "r": return "\r";
+      case "t": return "\t";
+      case "u":
+        var code;
+        if (seq.length == 5) {
+            code = seq.slice(1);
+        } else if (seq[1] == "{" && seq.slice(-1) == "}") {
+            code = seq.slice(2, -1);
+        } else {
+            return;
+        }
+        var num = parseInt(code, 16);
+        if (num < 0 || isNaN(num)) return;
+        if (num < 0x10000) return String.fromCharCode(num);
+        if (num > 0x10ffff) return;
+        return String.fromCharCode((num >> 10) + 0xd7c0) + String.fromCharCode((num & 0x03ff) + 0xdc00);
+      case "v": return "\u000b";
+      case "x":
+        if (seq.length != 3) return;
+        var num = parseInt(seq.slice(1), 16);
+        if (num < 0 || isNaN(num)) return;
+        return String.fromCharCode(num);
+      case "\r":
+      case "\n":
+        return "";
+      default:
+        if (seq == "0") return "\0";
+        if (seq[0] >= "0" && seq[0] <= "9") return;
+        return seq;
+    }
+}
+
 function parse_js_number(num) {
     var match;
     if (match = RE_BIN_NUMBER.exec(num)) return parseInt(match[1], 2);
@@ -340,36 +377,23 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
     }
 
     function read_escaped_char(in_string) {
-        var ch = next(true, in_string);
-        switch (ch.charCodeAt(0)) {
-          case 110: return "\n";
-          case 114: return "\r";
-          case 116: return "\t";
-          case 98:  return "\b";
-          case 118: return "\u000b";                            // \v
-          case 102: return "\f";
-          case 120: return String.fromCharCode(hex_bytes(2));   // \x
-          case 117:                                             // \u
-            if (peek() != "{") return String.fromCharCode(hex_bytes(4));
-            next();
-            var num = 0;
-            do {
-                var digit = parseInt(next(true), 16);
-                if (isNaN(digit)) parse_error("Invalid hex-character pattern in string");
-                num = num * 16 + digit;
-            } while (peek() != "}");
-            next();
-            if (num < 0x10000) return String.fromCharCode(num);
-            if (num > 0x10ffff) parse_error("Invalid character code: " + num);
-            return String.fromCharCode((num >> 10) + 0xd7c0) + String.fromCharCode((num & 0x03ff) + 0xdc00);
-          case 13:                                              // \r
-            // DOS newline
-            if (peek() == "\n") next(true, in_string);
-          case 10:  return "";                                  // \n
-        }
-        if (ch >= "0" && ch <= "7")
-            return read_octal_escape_sequence(ch);
-        return ch;
+        var seq = next(true, in_string);
+        if (seq >= "0" && seq <= "7") return read_octal_escape_sequence(seq);
+        if (seq == "u") {
+            var ch = next(true, in_string);
+            seq += ch;
+            if (ch != "{") {
+                seq += next(true, in_string) + next(true, in_string) + next(true, in_string);
+            } else do {
+                ch = next(true, in_string);
+                seq += ch;
+            } while (ch != "}");
+        } else if (seq == "x") {
+            seq += next(true, in_string) + next(true, in_string);
+        }
+        var str = decode_escape_sequence(seq);
+        if (typeof str != "string") parse_error("Invalid escape sequence: \\" + seq);
+        return str;
     }
 
     function read_octal_escape_sequence(ch) {
@@ -388,17 +412,6 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         return String.fromCharCode(parseInt(ch, 8));
     }
 
-    function hex_bytes(n) {
-        var num = 0;
-        for (; n > 0; --n) {
-            var digit = parseInt(next(true), 16);
-            if (isNaN(digit))
-                parse_error("Invalid hex-character pattern in string");
-            num = (num << 4) | digit;
-        }
-        return num;
-    }
-
     var read_string = with_eof_error("Unterminated string constant", function(quote_char) {
         var quote = next(), ret = "";
         for (;;) {
-- 
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