Add basic CommonJS support (#748)

Author: sandersn

internal/ast/ast.go

@@ -357,7 +357,7 @@ func (n *Node) Expression() *Node {
 		return n.AsThrowStatement().Expression
 	case KindExternalModuleReference:
 		return n.AsExternalModuleReference().Expression
-	case KindExportAssignment:
+	case KindExportAssignment, KindJSExportAssignment:
 		return n.AsExportAssignment().Expression
 	case KindDecorator:
 		return n.AsDecorator().Expression
@@ -532,7 +532,7 @@ func (n *Node) Type() *Node {
 		return n.AsJSDocNonNullableType().Type
 	case KindJSDocOptionalType:
 		return n.AsJSDocOptionalType().Type
-	case KindEnumMember, KindBindingElement, KindExportAssignment, KindBinaryExpression:
+	case KindEnumMember, KindBindingElement, KindExportAssignment, KindJSExportAssignment, KindBinaryExpression, KindCommonJSExport:
 		return nil
 	default:
 		funcLike := n.FunctionLikeData()
@@ -907,6 +907,10 @@ func (n *Node) AsExportAssignment() *ExportAssignment {
 	return n.data.(*ExportAssignment)
 }
 
+func (n *Node) AsCommonJSExport() *CommonJSExport {
+	return n.data.(*CommonJSExport)
+}
+
 func (n *Node) AsObjectLiteralExpression() *ObjectLiteralExpression {
 	return n.data.(*ObjectLiteralExpression)
 }
@@ -4314,6 +4318,7 @@ func IsNamedImports(node *Node) bool {
 
 // This is either an `export =` or an `export default` declaration.
 // Unless `isExportEquals` is set, this node was parsed as an `export default`.
+// If Kind is KindJSExportAssignment, it is a synthetic declaration for `module.exports =`.
 type ExportAssignment struct {
 	StatementBase
 	DeclarationBase
@@ -4323,17 +4328,25 @@ type ExportAssignment struct {
 	Expression     *Expression // Expression
 }
 
-func (f *NodeFactory) NewExportAssignment(modifiers *ModifierList, isExportEquals bool, expression *Expression) *Node {
+func (f *NodeFactory) newExportOrJSExportAssignment(kind Kind, modifiers *ModifierList, isExportEquals bool, expression *Expression) *Node {
 	data := &ExportAssignment{}
 	data.modifiers = modifiers
 	data.IsExportEquals = isExportEquals
 	data.Expression = expression
-	return f.newNode(KindExportAssignment, data)
+	return f.newNode(kind, data)
+}
+
+func (f *NodeFactory) NewExportAssignment(modifiers *ModifierList, isExportEquals bool, expression *Expression) *Node {
+	return f.newExportOrJSExportAssignment(KindExportAssignment, modifiers, isExportEquals, expression)
+}
+
+func (f *NodeFactory) NewJSExportAssignment(expression *Expression) *Node {
+	return f.newExportOrJSExportAssignment(KindJSExportAssignment, nil /*modifiers*/, true, expression)
 }
 
 func (f *NodeFactory) UpdateExportAssignment(node *ExportAssignment, modifiers *ModifierList, expression *Expression) *Node {
 	if modifiers != node.modifiers || expression != node.Expression {
-		return updateNode(f.NewExportAssignment(modifiers, node.IsExportEquals, expression), node.AsNode(), f.hooks)
+		return updateNode(f.newExportOrJSExportAssignment(node.Kind, modifiers, node.IsExportEquals, expression), node.AsNode(), f.hooks)
 	}
 	return node.AsNode()
 }
@@ -4347,7 +4360,7 @@ func (node *ExportAssignment) VisitEachChild(v *NodeVisitor) *Node {
 }
 
 func (node *ExportAssignment) Clone(f NodeFactoryCoercible) *Node {
-	return cloneNode(f.AsNodeFactory().NewExportAssignment(node.Modifiers(), node.IsExportEquals, node.Expression), node.AsNode(), f.AsNodeFactory().hooks)
+	return cloneNode(f.AsNodeFactory().newExportOrJSExportAssignment(node.Kind, node.Modifiers(), node.IsExportEquals, node.Expression), node.AsNode(), f.AsNodeFactory().hooks)
 }
 
 func (node *ExportAssignment) computeSubtreeFacts() SubtreeFacts {
@@ -4358,6 +4371,60 @@ func IsExportAssignment(node *Node) bool {
 	return node.Kind == KindExportAssignment
 }
 
+func IsJSExportAssignment(node *Node) bool {
+	return node.Kind == KindJSExportAssignment
+}
+
+func IsAnyExportAssignment(node *Node) bool {
+	return node.Kind == KindExportAssignment || node.Kind == KindJSExportAssignment
+}
+
+// CommonJSExport
+
+type CommonJSExport struct {
+	StatementBase
+	DeclarationBase
+	ExportableBase
+	ModifiersBase
+	name        *IdentifierNode
+	Initializer *Expression
+}
+
+func (f *NodeFactory) NewCommonJSExport(modifiers *ModifierList, name *IdentifierNode, initializer *Expression) *Node {
+	data := &CommonJSExport{}
+	data.modifiers = modifiers
+	data.name = name
+	data.Initializer = initializer
+	return newNode(KindCommonJSExport, data, f.hooks)
+}
+
+func (f *NodeFactory) UpdateCommonJSExport(node *CommonJSExport, modifiers *ModifierList, name *IdentifierNode, initializer *Expression) *Node {
+	if modifiers != node.modifiers || initializer != node.Initializer || name != node.name {
+		return updateNode(f.NewCommonJSExport(node.modifiers, name, initializer), node.AsNode(), f.hooks)
+	}
+	return node.AsNode()
+}
+
+func (node *CommonJSExport) ForEachChild(v Visitor) bool {
+	return visitModifiers(v, node.modifiers) || visit(v, node.name) || visit(v, node.Initializer)
+}
+
+func (node *CommonJSExport) VisitEachChild(v *NodeVisitor) *Node {
+	return v.Factory.UpdateCommonJSExport(node, v.visitModifiers(node.modifiers), v.visitNode(node.name), v.visitNode(node.Initializer))
+}
+
+func (node *CommonJSExport) Clone(f NodeFactoryCoercible) *Node {
+	return cloneNode(f.AsNodeFactory().NewCommonJSExport(node.Modifiers(), node.name, node.Initializer), node.AsNode(), f.AsNodeFactory().hooks)
+}
+
+func IsCommonJSExport(node *Node) bool {
+	return node.Kind == KindCommonJSExport
+}
+
+func (node *CommonJSExport) Name() *DeclarationName {
+	return node.name
+}
+
 // NamespaceExportDeclaration
 
 type NamespaceExportDeclaration struct {

internal/ast/kind.go

@@ -377,8 +377,10 @@ const (
 	KindJSDocImportTag
 	// Synthesized list
 	KindSyntaxList
-	// Synthesized JS nodes
+	// Reparsed JS nodes
 	KindJSTypeAliasDeclaration
+	KindJSExportAssignment
+	KindCommonJSExport
 	// Transformation nodes
 	KindNotEmittedStatement
 	KindPartiallyEmittedExpression

internal/ast/kind_stringer_generated.go

@@ -49,6 +49,7 @@ const (
 	InternalSymbolNameExportEquals            = "export=" // Export assignment symbol
 	InternalSymbolNameDefault                 = "default" // Default export symbol (technically not wholly internal, but included here for usability)
 	InternalSymbolNameThis                    = "this"
+	InternalSymbolNameModuleExports           = "module.exports"
 )
 
 func SymbolName(symbol *Symbol) string {

internal/ast/symbol.go

@@ -649,6 +649,7 @@ func isDeclarationStatementKind(kind Kind) bool {
 		KindImportEqualsDeclaration,
 		KindExportDeclaration,
 		KindExportAssignment,
+		KindJSExportAssignment,
 		KindNamespaceExportDeclaration:
 		return true
 	}
@@ -1304,7 +1305,7 @@ func GetElementOrPropertyAccessArgumentExpressionOrName(node *Node) *Node {
 }
 
 func GetElementOrPropertyAccessName(node *Node) string {
-	name := getElementOrPropertyAccessArgumentExpressionOrName(node)
+	name := GetElementOrPropertyAccessArgumentExpressionOrName(node)
 	if name == nil {
 		return ""
 	}
@@ -1351,10 +1352,10 @@ func GetNonAssignedNameOfDeclaration(declaration *Node) *Node {
 	switch declaration.Kind {
 	case KindBinaryExpression:
 		if IsFunctionPropertyAssignment(declaration) {
-			return getElementOrPropertyAccessArgumentExpressionOrName(declaration.AsBinaryExpression().Left)
+			return GetElementOrPropertyAccessArgumentExpressionOrName(declaration.AsBinaryExpression().Left)
 		}
 		return nil
-	case KindExportAssignment:
+	case KindExportAssignment, KindJSExportAssignment:
 		expr := declaration.AsExportAssignment().Expression
 		if IsIdentifier(expr) {
 			return expr
@@ -1414,22 +1415,6 @@ func IsFunctionPropertyAssignment(node *Node) bool {
 	return false
 }
 
-// Does not handle signed numeric names like `a[+0]` - handling those would require handling prefix unary expressions
-// throughout late binding handling as well, which is awkward (but ultimately probably doable if there is demand)
-func getElementOrPropertyAccessArgumentExpressionOrName(node *Node) *Node {
-	switch node.Kind {
-	case KindPropertyAccessExpression:
-		return node.Name()
-	case KindElementAccessExpression:
-		arg := SkipParentheses(node.AsElementAccessExpression().ArgumentExpression)
-		if IsStringOrNumericLiteralLike(arg) {
-			return arg
-		}
-		return node
-	}
-	panic("Unhandled case in getElementOrPropertyAccessArgumentExpressionOrName")
-}
-
 /**
  * A declaration has a dynamic name if all of the following are true:
  *   1. The declaration has a computed property name.
@@ -1495,10 +1480,6 @@ func IsEffectiveExternalModule(node *SourceFile, compilerOptions *core.CompilerO
 	return IsExternalModule(node) || (isCommonJSContainingModuleKind(compilerOptions.GetEmitModuleKind()) && node.CommonJSModuleIndicator != nil)
 }
 
-func IsEffectiveExternalModuleWorker(node *SourceFile, moduleKind core.ModuleKind) bool {
-	return IsExternalModule(node) || (isCommonJSContainingModuleKind(moduleKind) && node.CommonJSModuleIndicator != nil)
-}
-
 func isCommonJSContainingModuleKind(kind core.ModuleKind) bool {
 	return kind == core.ModuleKindCommonJS || kind == core.ModuleKindNode16 || kind == core.ModuleKindNodeNext
 }
@@ -1668,20 +1649,7 @@ func IsEnumConst(node *Node) bool {
 }
 
 func ExportAssignmentIsAlias(node *Node) bool {
-	return isAliasableExpression(getExportAssignmentExpression(node))
-}
-
-func getExportAssignmentExpression(node *Node) *Node {
-	switch node.Kind {
-	case KindExportAssignment:
-		return node.AsExportAssignment().Expression
-	case KindBinaryExpression:
-		return node.AsBinaryExpression().Right
-	}
-	panic("Unhandled case in getExportAssignmentExpression")
-}
-
-func isAliasableExpression(e *Node) bool {
+	e := node.AsExportAssignment().Expression
 	return IsEntityNameExpression(e) || IsClassExpression(e)
 }
 
@@ -2086,6 +2054,7 @@ func GetMeaningFromDeclaration(node *Node) SemanticMeaning {
 		KindImportEqualsDeclaration,
 		KindImportDeclaration,
 		KindExportAssignment,
+		KindJSExportAssignment,
 		KindExportDeclaration:
 		return SemanticMeaningAll
 
@@ -2474,22 +2443,27 @@ func IsNonLocalAlias(symbol *Symbol, excludes SymbolFlags) bool {
 // An alias symbol is created by one of the following declarations:
 //
 //	import <symbol> = ...
+//	const <symbol> = ... (JS only)
+//	const { <symbol>, ... } = ... (JS only)
 //	import <symbol> from ...
 //	import * as <symbol> from ...
 //	import { x as <symbol> } from ...
 //	export { x as <symbol> } from ...
 //	export * as ns <symbol> from ...
 //	export = <EntityNameExpression>
 //	export default <EntityNameExpression>
+//	module.exports = <EntityNameExpression> (JS only)
 func IsAliasSymbolDeclaration(node *Node) bool {
 	switch node.Kind {
 	case KindImportEqualsDeclaration, KindNamespaceExportDeclaration, KindNamespaceImport, KindNamespaceExport,
 		KindImportSpecifier, KindExportSpecifier:
 		return true
 	case KindImportClause:
 		return node.AsImportClause().Name() != nil
-	case KindExportAssignment:
+	case KindExportAssignment, KindJSExportAssignment:
 		return ExportAssignmentIsAlias(node)
+	case KindVariableDeclaration, KindBindingElement:
+		return IsVariableDeclarationInitializedToRequire(node)
 	}
 	return false
 }
@@ -2568,7 +2542,7 @@ func ForEachDynamicImportOrRequireCall(
 	lastIndex, size := findImportOrRequire(file.Text(), 0)
 	for lastIndex >= 0 {
 		node := GetNodeAtPosition(file, lastIndex, isJavaScriptFile && includeTypeSpaceImports)
-		if isJavaScriptFile && IsRequireCall(node, requireStringLiteralLikeArgument) {
+		if isJavaScriptFile && IsRequireCall(node) {
 			if cb(node, node.Arguments()[0]) {
 				return true
 			}
@@ -2595,7 +2569,8 @@ func ForEachDynamicImportOrRequireCall(
 	return false
 }
 
-func IsRequireCall(node *Node, requireStringLiteralLikeArgument bool) bool {
+// IsVariableDeclarationInitializedToRequire should be used wherever parent pointers are set
+func IsRequireCall(node *Node) bool {
 	if !IsCallExpression(node) {
 		return false
 	}
@@ -2606,7 +2581,7 @@ func IsRequireCall(node *Node, requireStringLiteralLikeArgument bool) bool {
 	if len(call.Arguments.Nodes) != 1 {
 		return false
 	}
-	return !requireStringLiteralLikeArgument || IsStringLiteralLike(call.Arguments.Nodes[0])
+	return IsStringLiteralLike(call.Arguments.Nodes[0])
 }
 
 func IsUnterminatedLiteral(node *Node) bool {
@@ -2664,6 +2639,36 @@ func GetPragmaArgument(pragma *Pragma, name string) string {
 	return ""
 }
 
+// Of the form: `const x = require("x")` or `const { x } = require("x")` or with `var` or `let`
+// The variable must not be exported and must not have a type annotation, even a jsdoc one.
+// The initializer must be a call to `require` with a string literal or a string literal-like argument.
+func IsVariableDeclarationInitializedToRequire(node *Node) bool {
+	if !IsInJSFile(node) {
+		return false
+	}
+	if node.Kind == KindBindingElement {
+		node = node.Parent.Parent
+	}
+	if node.Kind != KindVariableDeclaration {
+		return false
+	}
+
+	return node.Parent.Parent.ModifierFlags()&ModifierFlagsExport == 0 &&
+		node.AsVariableDeclaration().Initializer != nil &&
+		node.Type() == nil &&
+		IsRequireCall(node.AsVariableDeclaration().Initializer)
+}
+
+func IsModuleExportsAccessExpression(node *Node) bool {
+	return (IsPropertyAccessExpression(node) || isLiteralLikeElementAccess(node)) &&
+		IsModuleIdentifier(node.Expression()) &&
+		GetElementOrPropertyAccessName(node) == "exports"
+}
+
+func isLiteralLikeElementAccess(node *Node) bool {
+	return node.Kind == KindElementAccessExpression && IsStringOrNumericLiteralLike(node.AsElementAccessExpression().ArgumentExpression)
+}
+
 func IsCheckJSEnabledForFile(sourceFile *SourceFile, compilerOptions *core.CompilerOptions) bool {
 	if sourceFile.CheckJsDirective != nil {
 		return sourceFile.CheckJsDirective.Enabled