Method TryInsertTypeAnnotation

internal/ls/change/tracker.go:200–235

TryInsertTypeAnnotation inserts a type annotation after the appropriate position on a node (after the close paren for function-like, after the name/exclamation/question for variable-like). Returns true if successful.

(sourceFile *ast.SourceFile, node *ast.Node, typeNode *ast.Node)

// (after the close paren for function-like, after the name/exclamation/question for variable-like).
// Returns true if successful.
func (t *Tracker) TryInsertTypeAnnotation(sourceFile *ast.SourceFile, node *ast.Node, typeNode *ast.Node) bool {
	var endNode *ast.Node
	if ast.IsFunctionLike(node) {
		endNode = astnav.FindChildOfKind(node, ast.KindCloseParenToken, sourceFile)
		if endNode == nil {
			if !ast.IsArrowFunction(node) {
				return false
			}
			// If no `)`, is an arrow function `x => x`, so use the end of the first parameter
			params := node.Parameters()
			if len(params) == 0 {
				return false
			}
			endNode = params[0]
		}
	} else {
		switch node.Kind {
		case ast.KindVariableDeclaration:
			endNode = node.AsVariableDeclaration().ExclamationToken
		case ast.KindPropertySignature:
			endNode = node.AsPropertySignatureDeclaration().PostfixToken
		case ast.KindPropertyDeclaration:
			endNode = node.AsPropertyDeclaration().PostfixToken
		case ast.KindParameter:
			endNode = node.AsParameterDeclaration().QuestionToken
		}
		if endNode == nil {
			endNode = node.Name()
		}
	}
	if endNode == nil {
		return false
	}
	t.InsertNodeAt(sourceFile, core.TextPos(endNode.End()), typeNode, NodeOptions{Prefix: ": "})
	return true
}

// ParenthesizeArrowParameters wraps the parameters of a paren-less arrow function in `(` and `)`.
// This is a no-op if the arrow function already has parens.