vue3-yuanma/packages/compiler-core/src/codegen.ts

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import {
RootNode,
TemplateChildNode,
TextNode,
CommentNode,
ExpressionNode,
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NodeTypes,
JSChildNode,
CallExpression,
ArrayExpression,
ObjectExpression,
SourceLocation,
Position,
InterpolationNode,
CompoundExpressionNode,
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SimpleExpressionNode,
FunctionExpression,
SequenceExpression,
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ConditionalExpression,
CacheExpression
} from './ast'
import { SourceMapGenerator, RawSourceMap } from 'source-map'
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import {
advancePositionWithMutation,
assert,
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isSimpleIdentifier,
loadDep,
toValidAssetId
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} from './utils'
import { isString, isArray, isSymbol } from '@vue/shared'
import {
helperNameMap,
TO_STRING,
CREATE_VNODE,
RESOLVE_COMPONENT,
RESOLVE_DIRECTIVE,
SET_BLOCK_TRACKING,
CREATE_COMMENT
} from './runtimeHelpers'
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type CodegenNode = TemplateChildNode | JSChildNode
export interface CodegenOptions {
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// - Module mode will generate ES module import statements for helpers
// and export the render function as the default export.
// - Function mode will generate a single `const { helpers... } = Vue`
// statement and return the render function. It is meant to be used with
// `new Function(code)()` to generate a render function at runtime.
// Default: 'function'
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mode?: 'module' | 'function'
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// Prefix suitable identifiers with _ctx.
// If this option is false, the generated code will be wrapped in a
// `with (this) { ... }` block.
// Default: false
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prefixIdentifiers?: boolean
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// Generate source map?
// Default: false
sourceMap?: boolean
// Filename for source map generation.
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// Default: `template.vue.html`
filename?: string
}
export interface CodegenResult {
code: string
ast: RootNode
map?: RawSourceMap
}
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export interface CodegenContext extends Required<CodegenOptions> {
source: string
code: string
line: number
column: number
offset: number
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indentLevel: number
map?: SourceMapGenerator
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helper(key: symbol): string
push(code: string, node?: CodegenNode, openOnly?: boolean): void
resetMapping(loc: SourceLocation): void
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indent(): void
deindent(withoutNewLine?: boolean): void
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newline(): void
}
function createCodegenContext(
ast: RootNode,
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{
mode = 'function',
prefixIdentifiers = mode === 'module',
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sourceMap = false,
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filename = `template.vue.html`
}: CodegenOptions
): CodegenContext {
const context: CodegenContext = {
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mode,
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prefixIdentifiers,
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sourceMap,
filename,
source: ast.loc.source,
code: ``,
column: 1,
line: 1,
offset: 0,
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indentLevel: 0,
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// lazy require source-map implementation, only in non-browser builds!
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map:
__BROWSER__ || !sourceMap
? undefined
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: new (loadDep('source-map')).SourceMapGenerator(),
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helper(key) {
const name = helperNameMap[key]
return prefixIdentifiers ? name : `_${name}`
},
push(code, node, openOnly) {
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context.code += code
if (!__BROWSER__ && context.map) {
if (node) {
let name
if (node.type === NodeTypes.SIMPLE_EXPRESSION && !node.isStatic) {
const content = node.content.replace(/^_ctx\./, '')
if (content !== node.content && isSimpleIdentifier(content)) {
name = content
}
}
addMapping(node.loc.start, name)
}
advancePositionWithMutation(context, code)
if (node && !openOnly) {
addMapping(node.loc.end)
}
}
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},
resetMapping(loc: SourceLocation) {
if (!__BROWSER__ && context.map) {
addMapping(loc.start)
}
},
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indent() {
newline(++context.indentLevel)
},
deindent(withoutNewLine = false) {
if (withoutNewLine) {
--context.indentLevel
} else {
newline(--context.indentLevel)
}
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},
newline() {
newline(context.indentLevel)
}
}
function newline(n: number) {
context.push('\n' + ` `.repeat(n))
}
function addMapping(loc: Position, name?: string) {
context.map!.addMapping({
name,
source: context.filename,
original: {
line: loc.line,
column: loc.column - 1 // source-map column is 0 based
},
generated: {
line: context.line,
column: context.column - 1
}
})
}
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if (!__BROWSER__ && context.map) {
context.map.setSourceContent(filename, context.source)
}
return context
}
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export function generate(
ast: RootNode,
options: CodegenOptions = {}
): CodegenResult {
const context = createCodegenContext(ast, options)
const {
mode,
push,
helper,
prefixIdentifiers,
indent,
deindent,
newline
} = context
const hasHelpers = ast.helpers.length > 0
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const useWithBlock = !prefixIdentifiers && mode !== 'module'
// preambles
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if (mode === 'function') {
// Generate const declaration for helpers
// In prefix mode, we place the const declaration at top so it's done
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// only once; But if we not prefixing, we place the declaration inside the
// with block so it doesn't incur the `in` check cost for every helper access.
if (hasHelpers) {
if (prefixIdentifiers) {
push(`const { ${ast.helpers.map(helper).join(', ')} } = Vue\n`)
} else {
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// "with" mode.
// save Vue in a separate variable to avoid collision
push(`const _Vue = Vue\n`)
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// in "with" mode, helpers are declared inside the with block to avoid
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// has check cost, but hoists are lifted out of the function - we need
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// to provide the helper here.
if (ast.hoists.length) {
push(
`const _${helperNameMap[CREATE_VNODE]} = Vue.${
helperNameMap[CREATE_VNODE]
}\n`
)
if (ast.helpers.includes(CREATE_COMMENT)) {
push(
`const _${helperNameMap[CREATE_COMMENT]} = Vue.${
helperNameMap[CREATE_COMMENT]
}\n`
)
}
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}
}
}
genHoists(ast.hoists, context)
newline()
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push(`return `)
} else {
// generate import statements for helpers
if (hasHelpers) {
push(`import { ${ast.helpers.map(helper).join(', ')} } from "vue"\n`)
}
genHoists(ast.hoists, context)
newline()
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push(`export default `)
}
// enter render function
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push(`function render() {`)
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indent()
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if (useWithBlock) {
push(`with (this) {`)
indent()
// function mode const declarations should be inside with block
// also they should be renamed to avoid collision with user properties
if (hasHelpers) {
push(
`const { ${ast.helpers
.map(s => `${helperNameMap[s]}: _${helperNameMap[s]}`)
.join(', ')} } = _Vue`
)
newline()
if (ast.cached > 0) {
push(`const _cache = $cache`)
newline()
}
newline()
}
} else {
push(`const _ctx = this`)
if (ast.cached > 0) {
newline()
push(`const _cache = _ctx.$cache`)
}
newline()
}
// generate asset resolution statements
if (ast.components.length) {
genAssets(ast.components, 'component', context)
}
if (ast.directives.length) {
genAssets(ast.directives, 'directive', context)
}
if (ast.components.length || ast.directives.length) {
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newline()
}
// generate the VNode tree expression
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push(`return `)
if (ast.codegenNode) {
genNode(ast.codegenNode, context)
} else {
push(`null`)
}
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if (useWithBlock) {
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deindent()
push(`}`)
}
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deindent()
push(`}`)
return {
ast,
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code: context.code,
map: context.map ? context.map.toJSON() : undefined
}
}
function genAssets(
assets: string[],
type: 'component' | 'directive',
context: CodegenContext
) {
const resolver = context.helper(
type === 'component' ? RESOLVE_COMPONENT : RESOLVE_DIRECTIVE
)
for (let i = 0; i < assets.length; i++) {
const id = assets[i]
context.push(
`const ${toValidAssetId(id, type)} = ${resolver}(${JSON.stringify(id)})`
)
context.newline()
}
}
function genHoists(hoists: JSChildNode[], context: CodegenContext) {
if (!hoists.length) {
return
}
context.newline()
hoists.forEach((exp, i) => {
context.push(`const _hoisted_${i + 1} = `)
genNode(exp, context)
context.newline()
})
}
function isText(n: string | CodegenNode) {
return (
isString(n) ||
n.type === NodeTypes.SIMPLE_EXPRESSION ||
n.type === NodeTypes.TEXT ||
n.type === NodeTypes.INTERPOLATION ||
n.type === NodeTypes.COMPOUND_EXPRESSION
)
}
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function genNodeListAsArray(
nodes: (string | CodegenNode | TemplateChildNode[])[],
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context: CodegenContext
) {
const multilines =
nodes.length > 3 ||
((!__BROWSER__ || __DEV__) && nodes.some(n => isArray(n) || !isText(n)))
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context.push(`[`)
multilines && context.indent()
genNodeList(nodes, context, multilines)
multilines && context.deindent()
context.push(`]`)
}
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function genNodeList(
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nodes: (string | symbol | CodegenNode | TemplateChildNode[])[],
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context: CodegenContext,
multilines: boolean = false
) {
const { push, newline } = context
for (let i = 0; i < nodes.length; i++) {
const node = nodes[i]
if (isString(node)) {
push(node)
} else if (isArray(node)) {
genNodeListAsArray(node, context)
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} else {
genNode(node, context)
}
if (i < nodes.length - 1) {
if (multilines) {
push(',')
newline()
} else {
push(', ')
}
}
}
}
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function genNode(node: CodegenNode | symbol | string, context: CodegenContext) {
if (isString(node)) {
context.push(node)
return
}
if (isSymbol(node)) {
context.push(context.helper(node))
return
}
switch (node.type) {
case NodeTypes.ELEMENT:
case NodeTypes.IF:
case NodeTypes.FOR:
__DEV__ &&
assert(
node.codegenNode != null,
`Codegen node is missing for element/if/for node. ` +
`Apply appropriate transforms first.`
)
genNode(node.codegenNode!, context)
break
case NodeTypes.TEXT:
genText(node, context)
break
case NodeTypes.SIMPLE_EXPRESSION:
genExpression(node, context)
break
case NodeTypes.INTERPOLATION:
genInterpolation(node, context)
break
case NodeTypes.TEXT_CALL:
genNode(node.codegenNode, context)
break
case NodeTypes.COMPOUND_EXPRESSION:
genCompoundExpression(node, context)
break
case NodeTypes.COMMENT:
genComment(node, context)
break
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case NodeTypes.JS_CALL_EXPRESSION:
genCallExpression(node, context)
break
case NodeTypes.JS_OBJECT_EXPRESSION:
genObjectExpression(node, context)
break
case NodeTypes.JS_ARRAY_EXPRESSION:
genArrayExpression(node, context)
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break
case NodeTypes.JS_FUNCTION_EXPRESSION:
genFunctionExpression(node, context)
break
case NodeTypes.JS_SEQUENCE_EXPRESSION:
genSequenceExpression(node, context)
break
case NodeTypes.JS_CONDITIONAL_EXPRESSION:
genConditionalExpression(node, context)
break
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case NodeTypes.JS_CACHE_EXPRESSION:
genCacheExpression(node, context)
break
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/* istanbul ignore next */
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default:
if (__DEV__) {
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assert(false, `unhandled codegen node type: ${(node as any).type}`)
// make sure we exhaust all possible types
const exhaustiveCheck: never = node
return exhaustiveCheck
}
}
}
function genText(
node: TextNode | SimpleExpressionNode,
context: CodegenContext
) {
context.push(JSON.stringify(node.content), node)
}
function genExpression(node: SimpleExpressionNode, context: CodegenContext) {
const { content, isStatic } = node
context.push(isStatic ? JSON.stringify(content) : content, node)
}
function genInterpolation(node: InterpolationNode, context: CodegenContext) {
const { push, helper } = context
push(`${helper(TO_STRING)}(`)
genNode(node.content, context)
push(`)`)
}
function genCompoundExpression(
node: CompoundExpressionNode,
context: CodegenContext
) {
for (let i = 0; i < node.children!.length; i++) {
const child = node.children![i]
if (isString(child)) {
context.push(child)
} else {
genNode(child, context)
}
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}
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}
function genExpressionAsPropertyKey(
node: ExpressionNode,
context: CodegenContext
) {
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const { push } = context
if (node.type === NodeTypes.COMPOUND_EXPRESSION) {
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push(`[`)
genCompoundExpression(node, context)
push(`]`)
} else if (node.isStatic) {
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// only quote keys if necessary
const text = isSimpleIdentifier(node.content)
? node.content
: JSON.stringify(node.content)
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push(text, node)
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} else {
push(`[${node.content}]`, node)
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}
}
function genComment(node: CommentNode, context: CodegenContext) {
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if (__DEV__) {
const { push, helper } = context
push(`${helper(CREATE_COMMENT)}(${JSON.stringify(node.content)})`, node)
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}
}
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// JavaScript
function genCallExpression(node: CallExpression, context: CodegenContext) {
const callee = isString(node.callee)
? node.callee
: context.helper(node.callee)
context.push(callee + `(`, node, true)
genNodeList(node.arguments, context)
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context.push(`)`)
}
function genObjectExpression(node: ObjectExpression, context: CodegenContext) {
const { push, indent, deindent, newline, resetMapping } = context
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const { properties } = node
if (!properties.length) {
push(`{}`, node)
return
}
const multilines =
properties.length > 1 ||
((!__BROWSER__ || __DEV__) &&
properties.some(p => p.value.type !== NodeTypes.SIMPLE_EXPRESSION))
push(multilines ? `{` : `{ `)
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multilines && indent()
for (let i = 0; i < properties.length; i++) {
const { key, value, loc } = properties[i]
resetMapping(loc) // reset source mapping for every property.
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// key
genExpressionAsPropertyKey(key, context)
push(`: `)
// value
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genNode(value, context)
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if (i < properties.length - 1) {
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// will only reach this if it's multilines
push(`,`)
newline()
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}
}
multilines && deindent()
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push(multilines ? `}` : ` }`)
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}
function genArrayExpression(node: ArrayExpression, context: CodegenContext) {
genNodeListAsArray(node.elements, context)
}
function genFunctionExpression(
node: FunctionExpression,
context: CodegenContext
) {
const { push, indent, deindent } = context
const { params, returns, newline } = node
push(`(`, node)
if (isArray(params)) {
genNodeList(params, context)
} else if (params) {
genNode(params, context)
}
push(`) => `)
if (newline) {
push(`{`)
indent()
push(`return `)
}
if (isArray(returns)) {
genNodeListAsArray(returns, context)
} else {
genNode(returns, context)
}
if (newline) {
deindent()
push(`}`)
}
}
function genConditionalExpression(
node: ConditionalExpression,
context: CodegenContext
) {
const { test, consequent, alternate } = node
const { push, indent, deindent, newline } = context
if (test.type === NodeTypes.SIMPLE_EXPRESSION) {
const needsParens = !isSimpleIdentifier(test.content)
needsParens && push(`(`)
genExpression(test, context)
needsParens && push(`)`)
} else {
push(`(`)
genCompoundExpression(test, context)
push(`)`)
}
indent()
context.indentLevel++
push(`? `)
genNode(consequent, context)
context.indentLevel--
newline()
push(`: `)
const isNested = alternate.type === NodeTypes.JS_CONDITIONAL_EXPRESSION
if (!isNested) {
context.indentLevel++
}
genNode(alternate, context)
if (!isNested) {
context.indentLevel--
}
deindent(true /* without newline */)
}
function genSequenceExpression(
node: SequenceExpression,
context: CodegenContext
) {
context.push(`(`)
genNodeList(node.expressions, context)
context.push(`)`)
}
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function genCacheExpression(node: CacheExpression, context: CodegenContext) {
const { push, helper, indent, deindent, newline } = context
push(`_cache[${node.index}] || (`)
if (node.isVNode) {
indent()
push(`${helper(SET_BLOCK_TRACKING)}(-1),`)
newline()
}
push(`_cache[${node.index}] = `)
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genNode(node.value, context)
if (node.isVNode) {
push(`,`)
newline()
push(`${helper(SET_BLOCK_TRACKING)}(1),`)
newline()
push(`_cache[${node.index}]`)
deindent()
}
push(`)`)
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}