feat: add jsDoc typecast completions, add tests (#180)

Author: Ilanaya

typescript/src/completions/asSuggestions.ts

@@ -0,0 +1,40 @@
+import { findChildContainingExactPosition } from '../utils'
+import { sharedCompletionContext } from './sharedContext'
+
+const getCastedTypeCompletionEntry = (typeChecker: ts.TypeChecker, node: ts.Expression) => {
+    const typeAtLocation = typeChecker.getTypeAtLocation(node)
+    const type = typeChecker.typeToString(typeAtLocation)
+    const widenType = typeChecker.typeToString(typeChecker.getBaseTypeOfLiteralType(typeAtLocation))
+
+    return {
+        kind: ts.ScriptElementKind.unknown,
+        name: type === widenType ? type : widenType,
+        sortText: '!',
+    }
+}
+
+export default () => {
+    const typeChecker = sharedCompletionContext.program.getTypeChecker()
+    const { position, fullText, prior } = sharedCompletionContext
+
+    // as completions
+    if (fullText.slice(0, position - 1).endsWith('as')) {
+        const node = findChildContainingExactPosition(sharedCompletionContext.sourceFile, position - 2)
+        if (!node || !ts.isAsExpression(node)) return
+        const entry = getCastedTypeCompletionEntry(typeChecker, node.expression)
+        prior.entries.push(entry)
+        return
+    }
+
+    // jsdoc typecast completions
+    const node = findChildContainingExactPosition(sharedCompletionContext.sourceFile, position)
+    if (!node) return
+    let typeCastedNode: ts.ParenthesizedExpression | undefined
+    node.forEachChild(node => {
+        if (ts.isParenthesizedExpression(node) && ts.getJSDocTypeTag(node)) typeCastedNode = node
+    })
+
+    if (!typeCastedNode) return
+    const entry = getCastedTypeCompletionEntry(typeChecker, typeCastedNode.expression)
+    prior.entries.push(entry)
+}

typescript/src/completions/typecastCompletions.ts

@@ -31,7 +31,7 @@ import stringTemplateTypeCompletions from './completions/stringTemplateType'
 import localityBonus from './completions/localityBonus'
 import functionCompletions from './completions/functionCompletions'
 import staticHintSuggestions from './completions/staticHintSuggestions'
-import asSuggestions from './completions/asSuggestions'
+import typecastCompletions from './completions/typecastCompletions'
 
 export type PrevCompletionMap = Record<
     string,
@@ -300,7 +300,7 @@ export const getCompletionsAtPosition = (
     if (c('improveJsxCompletions') && leftNode) prior.entries = improveJsxCompletions(prior.entries, leftNode, position, sourceFile, c('jsxCompletionsMap'))
 
     prior.entries = localityBonus(prior.entries) ?? prior.entries
-    asSuggestions()
+    typecastCompletions()
     prior.entries.push(...(staticHintSuggestions() ?? []))
 
     const processedEntries = new Set<ts.CompletionEntry>()

typescript/src/completionsAtPosition.ts

@@ -860,3 +860,23 @@ test('In Keyword Completions', () => {
       }
     `)
 })
+describe('Typecast completions', () => {
+    test('As completions', () => {
+        const [pos] = newFileContents(/*ts*/ `
+            const b = 5
+            const a = b as /*|*/
+        `)
+        const completions = getCompletionsAtPosition(pos!)?.entriesSorted
+
+        expect(completions?.[0]?.name).toEqual('number')
+    })
+    test('jsDoc typecast', () => {
+        const [pos] = newFileContents(/*ts*/ `
+            const b = 5
+            const a = /** @type {/*|*/} */(b)
+        `)
+        const completions = getCompletionsAtPosition(pos!)?.entriesSorted
+
+        expect(completions?.[0]?.name).toEqual('number')
+    })
+})