feat(asSuggestions): add asSuggestions

Author: Ilya Golovin

typescript/src/completions/asSuggestions.ts

@@ -0,0 +1,26 @@
+import { findChildContainingExactPosition } from '../utils'
+import { sharedCompletionContext } from './sharedContext'
+
+export default () => {
+    const typeChecker = sharedCompletionContext.program.getTypeChecker()
+    const { position, fullText, prior } = sharedCompletionContext
+    if (!fullText.slice(0, position - 1).endsWith('as')) return
+    const node = findChildContainingExactPosition(sharedCompletionContext.sourceFile, position - 2)
+    if (!node || !ts.isAsExpression(node)) return
+    const typeAtLocation = typeChecker.getTypeAtLocation(node.expression)
+    const type = typeChecker.typeToString(typeAtLocation)
+    const widenType = typeChecker.typeToString(typeChecker.getBaseTypeOfLiteralType(typeAtLocation))
+
+    if (type !== widenType) {
+        prior.entries.push({
+            kind: ts.ScriptElementKind.unknown,
+            name: widenType,
+            sortText: '!',
+        })
+    }
+    prior.entries.push({
+        kind: ts.ScriptElementKind.unknown,
+        name: type,
+        sortText: '!',
+    })
+}

typescript/src/completions/sharedContext.ts

@@ -14,5 +14,6 @@ export const sharedCompletionContext = {} as unknown as Readonly<{
     c: GetConfig
     formatOptions: ts.FormatCodeSettings
     preferences: ts.UserPreferences
+    fullText: string
     // languageServiceHost: ts.LanguageServiceHost
 }>

typescript/src/completionsAtPosition.ts

@@ -31,6 +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'
 
 export type PrevCompletionMap = Record<
     string,
@@ -139,6 +140,7 @@ export const getCompletionsAtPosition = (
         formatOptions: formatOptions || {},
         preferences: options || {},
         prior: prior!,
+        fullText: sourceFile.getFullText(),
     } satisfies typeof sharedCompletionContext)
 
     if (node && !hasSuggestions && ensurePrior() && prior) {
@@ -296,9 +298,11 @@ 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()
     prior.entries.push(...(staticHintSuggestions() ?? []))
 
     const processedEntries = new Set<ts.CompletionEntry>()
+
     for (const rule of c('replaceSuggestions')) {
         if (rule.filter?.fileNamePattern) {
             // todo replace with something better