feat: more flexible squared property read expression, fixes #643 (#646)

* fix: more flexible squared property read expression, fixes #643

* fix: unecessary error wrapping in browser bundles

* style: update code style and types

* perf: use token.value when evalToken

src/render/string.ts

@@ -0,0 +1,49 @@
+const rHex = /[\da-fA-F]/
+const rOct = /[0-7]/
+const escapeChar = {
+  b: '\b',
+  f: '\f',
+  n: '\n',
+  r: '\r',
+  t: '\t',
+  v: '\x0B'
+}
+
+function hexVal (c: string) {
+  const code = c.charCodeAt(0)
+  if (code >= 97) return code - 87
+  if (code >= 65) return code - 55
+  return code - 48
+}
+
+export function parseStringLiteral (str: string): string {
+  let ret = ''
+  for (let i = 1; i < str.length - 1; i++) {
+    if (str[i] !== '\\') {
+      ret += str[i]
+      continue
+    }
+    if (escapeChar[str[i + 1]] !== undefined) {
+      ret += escapeChar[str[++i]]
+    } else if (str[i + 1] === 'u') {
+      let val = 0
+      let j = i + 2
+      while (j <= i + 5 && rHex.test(str[j])) {
+        val = val * 16 + hexVal(str[j++])
+      }
+      i = j - 1
+      ret += String.fromCharCode(val)
+    } else if (!rOct.test(str[i + 1])) {
+      ret += str[++i]
+    } else {
+      let j = i + 1
+      let val = 0
+      while (j <= i + 3 && rOct.test(str[j])) {
+        val = val * 8 + hexVal(str[j++])
+      }
+      i = j - 1
+      ret += String.fromCharCode(val)
+    }
+  }
+  return ret
+}