Update error parsing for latest V8

1 files changed, 114 insertions, 107 deletions

diff --git a/src/gleam_json_ffi.mjs b/src/gleam_json_ffi.mjs
index b60d848..85a81b0 100644
--- a/src/gleam_json_ffi.mjs
+++ b/src/gleam_json_ffi.mjs
@@ -1,46 +1,38 @@
-import { Ok, Error } from './gleam.mjs'
-import { UnexpectedByte, UnexpectedEndOfInput } from './gleam/json.mjs'
-
-const Runtime = {
-  chromium: 'chromium',
-  spidermonkey: 'spidermonkey',
-  jscore: 'jscore',
-}
+import { Ok, Error } from "./gleam.mjs";
+import { UnexpectedByte, UnexpectedEndOfInput } from "./gleam/json.mjs";
 
 export function json_to_string(json) {
-  return JSON.stringify(json)
+  return JSON.stringify(json);
 }
 
 export function object(entries) {
-  return Object.fromEntries(entries)
+  return Object.fromEntries(entries);
 }
 
 export function identity(x) {
-  return x
+  return x;
 }
 
 export function array(list) {
-  return list.toArray()
+  return list.toArray();
 }
 
 export function do_null() {
-  return null
+  return null;
 }
 
 export function decode(string) {
   try {
-    const result = JSON.parse(string)
-    return new Ok(result)
+    const result = JSON.parse(string);
+    return new Ok(result);
   } catch (err) {
-    return new Error(getJsonDecodeError(err, string))
+    return new Error(getJsonDecodeError(err, string));
   }
 }
 
 export function getJsonDecodeError(stdErr, json) {
-  if (isUnexpectedEndOfInput(stdErr)) return new UnexpectedEndOfInput()
-  const unexpectedByteRuntime = getUnexpectedByteRuntime(stdErr)
-  if (unexpectedByteRuntime) return toUnexpectedByteError(unexpectedByteRuntime, stdErr, json)
-  return new UnexpectedByte('', 0)
+  if (isUnexpectedEndOfInput(stdErr)) return new UnexpectedEndOfInput();
+  return toUnexpectedByteError(stdErr, json);
 }
 
 /**
@@ -48,139 +40,154 @@ export function getJsonDecodeError(stdErr, json) {
  * - Chromium (edge, chrome, node)
  * - Spidermonkey (firefox)
  * - JavascriptCore (safari)
- * 
+ *
  * Note that Spidermonkey and JavascriptCore will both incorrectly report some
  * UnexpectedByte errors as UnexpectedEndOfInput errors. For example:
- * 
+ *
  * @example
  * // in JavascriptCore
  * JSON.parse('{"a"]: "b"})
  * // => JSON Parse error: Expected ':' before value
- * 
+ *
  * JSON.parse('{"a"')
  * // => JSON Parse error: Expected ':' before value
- * 
+ *
  * // in Chromium (correct)
  * JSON.parse('{"a"]: "b"})
  * // => Unexpected token ] in JSON at position 4
- * 
+ *
  * JSON.parse('{"a"')
  * // => Unexpected end of JSON input
  */
-const unexpectedEndOfInputRegex = /((unexpected (end|eof))|(end of data)|(unterminated string)|(json( parse error|\.parse)\: expected '(\:|\}|\])'))/i
-
 function isUnexpectedEndOfInput(err) {
-  return unexpectedEndOfInputRegex.test(err.message)
+  const unexpectedEndOfInputRegex =
+    /((unexpected (end|eof))|(end of data)|(unterminated string)|(json( parse error|\.parse)\: expected '(\:|\}|\])'))/i;
+  return unexpectedEndOfInputRegex.test(err.message);
 }
 
+/**
+ * Converts a SyntaxError to an UnexpectedByte error based on the JS runtime.
+ *
+ * For Chromium, the unexpected byte and position are reported by the runtime.
+ *
+ * For JavascriptCore, only the unexpected byte is reported by the runtime, so
+ * there is no way to know which position that character is in unless we then
+ * parse the string again ourselves. So instead, the position is reported as 0.
+ *
+ * For Spidermonkey, the position is reported by the runtime as a line and column number
+ * and the unexpected byte is found using those coordinates.
+ *
+ * @param {'chromium' | 'spidermonkey' | 'jscore'} runtime
+ * @param {SyntaxError} err
+ * @param {string} json
+ * @returns {UnexpectedByte}
+ */
+function toUnexpectedByteError(err, json) {
+  let converters = [
+    v8UnexpectedByteError,
+    oldV8UnexpectedByteError,
+    jsCoreUnexpectedByteError,
+    spidermonkeyUnexpectedByteError,
+  ];
+
+  for (let converter of converters) {
+    let result = converter(err, json);
+    if (result) return result;
+  }
+
+  return new UnexpectedByte("", 0);
+}
 
 /**
  * Matches unexpected byte messages in:
- * - Chromium (edge, chrome, node)
- * 
- * Matches the character and its position.
+ * - V8 (edge, chrome, node)
+ *
+ * Matches the character but not the position as this is no longer reported by
+ * V8. Boo!
  */
-const chromiumUnexpectedByteRegex = /unexpected token (.) in JSON at position (\d+)/i
+function v8UnexpectedByteError(err) {
+  const regex = /unexpected token '(.)', ".+" is not valid JSON/i;
+  const match = regex.exec(err.message);
+  if (!match) return null;
+  const byte = toHex(match[1]);
+  return new UnexpectedByte(byte, -1);
+}
 
 /**
  * Matches unexpected byte messages in:
- * - JavascriptCore (safari)
- * 
- * JavascriptCore only reports what the character is and not its position.
+ * - V8 (edge, chrome, node)
+ *
+ * No longer works in current versions of V8.
+ *
+ * Matches the character and its position.
  */
-const jsCoreUnexpectedByteRegex = /unexpected (identifier|token) "(.)"/i
+function oldV8UnexpectedByteError(err) {
+  const regex = /unexpected token (.) in JSON at position (\d+)/i;
+  const match = regex.exec(err.message);
+  if (!match) return null;
+  const byte = toHex(match[1]);
+  const position = Number(match[2]);
+  return new UnexpectedByte(byte, position);
+}
 
 /**
  * Matches unexpected byte messages in:
  * - Spidermonkey (firefox)
- * 
+ *
  * Matches the position in a 2d grid only and not the character.
  */
-const spidermonkeyUnexpectedByteRegex = /(unexpected character|expected .*) at line (\d+) column (\d+)/i
-
-function getUnexpectedByteRuntime(err) {
-  if (chromiumUnexpectedByteRegex.test(err.message)) return Runtime.chromium
-  if (jsCoreUnexpectedByteRegex.test(err.message)) return Runtime.jscore
-  if (spidermonkeyUnexpectedByteRegex.test(err.message)) return Runtime.spidermonkey
-  return null
+function spidermonkeyUnexpectedByteError(err, json) {
+  const regex =
+    /(unexpected character|expected .*) at line (\d+) column (\d+)/i;
+  const match = regex.exec(err.message);
+  if (!match) return null;
+  const line = Number(match[2]);
+  const column = Number(match[3]);
+  const position = getPositionFromMultiline(line, column, json);
+  const byte = toHex(json[position]);
+  return new UnexpectedByte(byte, position);
 }
 
 /**
- * Converts a SyntaxError to an UnexpectedByte error based on the JS runtime.
- * 
- * For Chromium, the unexpected byte and position are reported by the runtime.
- * 
- * For JavascriptCore, only the unexpected byte is reported by the runtime, so
- * there is no way to know which position that character is in unless we then
- * parse the string again ourselves. So instead, the position is reported as 0.
- * 
- * For Spidermonkey, the position is reported by the runtime as a line and column number 
- * and the unexpected byte is found using those coordinates.
- * 
- * @param {'chromium' | 'spidermonkey' | 'jscore'} runtime 
- * @param {SyntaxError} err 
- * @param {string} json 
- * @returns {UnexpectedByte}
+ * Matches unexpected byte messages in:
+ * - JavascriptCore (safari)
+ *
+ * JavascriptCore only reports what the character is and not its position.
  */
-function toUnexpectedByteError(runtime, err, json) {
-  switch (runtime) {
-    case Runtime.chromium:
-      return toChromiumUnexpectedByteError(err)
-    case Runtime.spidermonkey:
-      return toSpidermonkeyUnexpectedByteError(err, json)
-    case Runtime.jscore:
-      return toJsCoreUnexpectedByteError(err)
-  }
-}
-
-function toChromiumUnexpectedByteError(err) {
-  const match = chromiumUnexpectedByteRegex.exec(err.message)
-  const byte = toHex(match[1])
-  const position = Number(match[2])
-  return new UnexpectedByte(byte, position)
-}
-
-function toSpidermonkeyUnexpectedByteError(err, json) {
-  const match = spidermonkeyUnexpectedByteRegex.exec(err.message)
-  const line = Number(match[2])
-  const column = Number(match[3])
-  const position = getPositionFromMultiline(line, column, json)
-  const byte = toHex(json[position])
-  return new UnexpectedByte(byte, position)
-}
-
-function toJsCoreUnexpectedByteError(err) {
-  const match = jsCoreUnexpectedByteRegex.exec(err.message)
-  const byte = toHex(match[2])
-  return new UnexpectedByte(byte, 0)
+function jsCoreUnexpectedByteError(err) {
+  const regex = /unexpected (identifier|token) "(.)"/i;
+  const match = regex.exec(err.message);
+  if (!match) return null;
+  const byte = toHex(match[2]);
+  return new UnexpectedByte(byte, 0);
 }
 
 function toHex(char) {
-  return "0x" + char.charCodeAt(0).toString(16).toUpperCase()
+  return "0x" + char.charCodeAt(0).toString(16).toUpperCase();
 }
 
 /**
  * Gets the position of a character in a flattened (i.e. single line) string
- * from a line and column number. Note that the position is 0-indexed and 
+ * from a line and column number. Note that the position is 0-indexed and
  * the line and column numbers are 1-indexed.
- * 
- * @param {number} line 
- * @param {number} column 
- * @param {string} string 
+ *
+ * @param {number} line
+ * @param {number} column
+ * @param {string} string
  */
 function getPositionFromMultiline(line, column, string) {
-  if (line === 1) return column - 1
+  if (line === 1) return column - 1;
 
-  let currentLn = 1
-  let position = 0
-  string.split('').find((char, idx) => {
-    if (char === '\n') currentLn += 1
+  let currentLn = 1;
+  let position = 0;
+  string.split("").find((char, idx) => {
+    if (char === "\n") currentLn += 1;
     if (currentLn === line) {
-      position = idx + column
-      return true
+      position = idx + column;
+      return true;
     }
-    return false
-  })
+    return false;
+  });
 
-  return position
-}
\ No newline at end of file
+  return position;
+}