feat(compiler): basic codegen with source map support

packages/compiler-core/src/codegen.ts

@@ -1 +1,165 @@
-// TODO
+import {
+  RootNode,
+  ChildNode,
+  ElementNode,
+  IfNode,
+  ForNode,
+  TextNode,
+  CommentNode,
+  ExpressionNode,
+  NodeTypes
+} from './ast'
+import { SourceMapGenerator, RawSourceMap } from 'source-map'
+import { advancePositionWithMutation } from './utils'
+
+export interface CodegenOptions {
+  // Assume ES module environment. If true, will generate import statements for
+  // runtime helpers; otherwise will grab the helpers from global `Vue`.
+  module?: boolean
+  // Filename for source map generation.
+  filename?: string
+}
+
+export interface CodegenResult {
+  code: string
+  map?: RawSourceMap
+}
+
+interface CodegenContext extends Required<CodegenOptions> {
+  source: string
+  code: string
+  line: number
+  column: number
+  offset: number
+  indent: number
+  identifiers: Set<string>
+  map?: SourceMapGenerator
+  push(generatedCode: string, astNode?: ChildNode): void
+}
+
+export function generate(
+  ast: RootNode,
+  options: CodegenOptions = {}
+): CodegenResult {
+  const context = createCodegenContext(ast, options)
+  if (context.module) {
+    // TODO inject import statements on RootNode
+    context.push(`export function render() {\n`)
+    context.indent++
+    context.push(`  return `)
+  }
+  if (ast.children.length === 1) {
+    genNode(ast.children[0], context)
+  } else {
+    genChildren(ast.children, context)
+  }
+  if (context.module) {
+    context.indent--
+    context.push(`\n}`)
+  }
+  return {
+    code: context.code,
+    map: context.map ? context.map.toJSON() : undefined
+  }
+}
+
+function createCodegenContext(
+  ast: RootNode,
+  options: CodegenOptions
+): CodegenContext {
+  const context: CodegenContext = {
+    module: true,
+    filename: `template.vue.html`,
+    ...options,
+    source: ast.loc.source,
+    code: ``,
+    column: 1,
+    line: 1,
+    offset: 0,
+    indent: 0,
+    identifiers: new Set(),
+    // lazy require source-map implementation, only in non-browser builds!
+    map: __BROWSER__
+      ? undefined
+      : new (require('source-map')).SourceMapGenerator(),
+    push(generatedCode, node) {
+      // TODO handle indent
+      context.code += generatedCode
+      if (context.map) {
+        if (node) {
+          context.map.addMapping({
+            source: context.filename,
+            original: {
+              line: node.loc.start.line,
+              column: node.loc.start.column - 1 // source-map column is 0 based
+            },
+            generated: {
+              line: context.line,
+              column: context.column - 1
+            }
+          })
+        }
+        advancePositionWithMutation(
+          context,
+          generatedCode,
+          generatedCode.length
+        )
+      }
+    }
+  }
+  return context
+}
+
+function genChildren(children: ChildNode[], context: CodegenContext) {
+  context.push(`[`)
+  for (let i = 0; i < children.length; i++) {
+    genNode(children[i], context)
+    if (i < children.length - 1) context.push(', ')
+  }
+  context.push(`]`)
+}
+
+function genNode(node: ChildNode, context: CodegenContext) {
+  switch (node.type) {
+    case NodeTypes.ELEMENT:
+      genElement(node, context)
+      break
+    case NodeTypes.TEXT:
+      genText(node, context)
+      break
+    case NodeTypes.EXPRESSION:
+      genExpression(node, context)
+      break
+    case NodeTypes.COMMENT:
+      genComment(node, context)
+      break
+    case NodeTypes.IF:
+      genIf(node, context)
+      break
+    case NodeTypes.FOR:
+      genFor(node, context)
+      break
+  }
+}
+
+function genElement(el: ElementNode, context: CodegenContext) {}
+
+function genText(node: TextNode | ExpressionNode, context: CodegenContext) {
+  context.push(JSON.stringify(node.content), node)
+}
+
+function genExpression(node: ExpressionNode, context: CodegenContext) {
+  if (!__BROWSER__) {
+    // TODO parse expression content and rewrite identifiers
+  }
+  context.push(node.content, node)
+}
+
+function genComment(node: CommentNode, context: CodegenContext) {
+  context.push(`<!--${node.content}-->`, node)
+}
+
+// control flow
+function genIf(node: IfNode, context: CodegenContext) {}
+
+function genFor(node: ForNode, context: CodegenContext) {}