feat: clean string module lex string template

packages/vite/src/node/__tests__/cleanString.spec.ts

@@ -106,3 +106,55 @@ test('find empty string flag in raw index', () => {
   const bStart = clean.indexOf('\0\0\0\0\0', bIndex)
   expect(str.slice(bStart, bStart + 5)).toMatch('bbbbb')
 })
+
+test('template string nested', () => {
+  let str = '`aaaa`'
+  let res = '`\0\0\0\0`'
+  let clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aaaa` `aaaa`'
+  res = '`\0\0\0\0` `\0\0\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aa${a}aa`'
+  res = '`\0\0${a}\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aa${a + `a` + a}aa`'
+  res = '`\0\0${a + `\0` + a}\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aa${a + `a` + a}aa` `aa${a + `a` + a}aa`'
+  res = '`\0\0${a + `\0` + a}\0\0` `\0\0${a + `\0` + a}\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aa${a + `aaaa${c + (a = {b: 1}) + d}` + a}aa`'
+  res = '`\0\0${a + `\0\0\0\0${c + (a = {b: 1}) + d}` + a}\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str =
+    '`aa${a + `aaaa${c + (a = {b: 1}) + d}` + a}aa` `aa${a + `aaaa${c + (a = {b: 1}) + d}` + a}aa`'
+  res =
+    '`\0\0${a + `\0\0\0\0${c + (a = {b: 1}) + d}` + a}\0\0` `\0\0${a + `\0\0\0\0${c + (a = {b: 1}) + d}` + a}\0\0`'
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+
+  str = '`aaaa'
+  res = ''
+  try {
+    clean = emptyString(str)
+  } catch {}
+  expect(clean).toMatch(res)
+
+  str =
+    "<img src=\"${new URL('../assets/images/loading/loading.gif', import.meta.url).href}\" alt=''>"
+  res = `<img src="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" alt=''>`
+  clean = emptyString(str)
+  expect(clean).toMatch(res)
+})

packages/vite/src/node/cleanString.ts

@@ -1,3 +1,4 @@
+import type { RollupError } from 'rollup'
 // bank on the non-overlapping nature of regex matches and combine all filters into one giant regex
 // /`([^`\$\{\}]|\$\{(`|\g<1>)*\})*`/g can match nested string template
 // but js not support match expression(\g<0>). so clean string template(`...`) in other ways.
@@ -8,7 +9,117 @@ const stringBlankReplacer = (s: string) =>
   `${s[0]}${'\0'.repeat(s.length - 2)}${s[0]}`
 
 export function emptyString(raw: string): string {
-  return raw.replace(cleanerRE, (s: string) =>
+  let res = raw.replace(cleanerRE, (s: string) =>
     s[0] === '/' ? blankReplacer(s) : stringBlankReplacer(s)
   )
+
+  let lastEnd = 0
+  let start = 0
+  while ((start = res.indexOf('`', lastEnd)) >= 0) {
+    let clean
+    ;[clean, lastEnd] = lexStringTemplateExpression(res, start)
+    res = replaceAt(res, start, lastEnd, clean)
+  }
+
+  return res
+}
+
+const enum LexerState {
+  inTemplateString,
+  inInterpolationExpression,
+  inObjectExpression
+}
+
+function replaceAt(
+  string: string,
+  start: number,
+  end: number,
+  replacement: string
+): string {
+  return string.slice(0, start) + replacement + string.slice(end)
+}
+
+/**
+ * lex string template and clean it.
+ */
+function lexStringTemplateExpression(
+  code: string,
+  start: number
+): [string, number] {
+  let state = LexerState.inTemplateString as LexerState
+  let clean = '`'
+  const opStack: LexerState[] = [state]
+
+  function pushStack(newState: LexerState) {
+    state = newState
+    opStack.push(state)
+  }
+
+  function popStack() {
+    opStack.pop()
+    state = opStack[opStack.length - 1]
+  }
+
+  let i = start + 1
+  outer: for (; i < code.length; i++) {
+    const char = code.charAt(i)
+    switch (state) {
+      case LexerState.inTemplateString:
+        if (char === '$' && code.charAt(i + 1) === '{') {
+          pushStack(LexerState.inInterpolationExpression)
+          clean += '${'
+          i++ // jump next
+        } else if (char === '`') {
+          popStack()
+          clean += char
+          if (opStack.length === 0) {
+            break outer
+          }
+        } else {
+          clean += '\0'
+        }
+        break
+      case LexerState.inInterpolationExpression:
+        if (char === '{') {
+          pushStack(LexerState.inObjectExpression)
+          clean += char
+        } else if (char === '}') {
+          popStack()
+          clean += char
+        } else if (char === '`') {
+          pushStack(LexerState.inTemplateString)
+          clean += char
+        } else {
+          clean += char
+        }
+        break
+      case LexerState.inObjectExpression:
+        if (char === '}') {
+          popStack()
+          clean += char
+        } else if (char === '`') {
+          pushStack(LexerState.inTemplateString)
+          clean += char
+        } else {
+          clean += char
+        }
+        break
+      default:
+        throw new Error('unknown string template lexer state')
+    }
+  }
+
+  if (opStack.length !== 0) {
+    error(start)
+  }
+
+  return [clean, i + 1]
+}
+
+function error(pos: number) {
+  const err = new Error(
+    `can not match string template expression.`
+  ) as RollupError
+  err.pos = pos
+  throw err
 }