WIP: Improve hover text for common kinds of symbols.

Author: varungandhi-src

src/FileIndexer.ts

@@ -143,7 +143,7 @@ export class FileIndexer {
   ): void {
     const documentation = [
       '```ts\n' +
-        this.checker.typeToString(this.checker.getTypeAtLocation(node)) +
+        this.signatureForDocumentation(node, sym) +
         '\n```',
     ]
     const docstring = sym.getDocumentationComment(this.checker)
@@ -331,6 +331,58 @@ export class FileIndexer {
     }
     return undefined
   }
+
+  private signatureForDocumentation(
+    node: ts.Node,
+    sym: ts.Symbol
+  ): string {
+    const kind = scriptElementKind(node, sym)
+    const type = (): string => this.checker.typeToString(this.checker.getTypeAtLocation(node))
+    switch (kind) {
+      case ts.ScriptElementKind.localVariableElement:
+      case ts.ScriptElementKind.variableElement:
+        return 'var ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.memberVariableElement:
+        return '(property) ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.parameterElement:
+        return '(parameter) ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.constElement:
+        return 'const ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.letElement:
+        return 'let ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.alias:
+        return 'type ' + node.getText()
+      case ts.ScriptElementKind.classElement:
+      case ts.ScriptElementKind.localClassElement:
+        return 'class ' + node.getText()
+      case ts.ScriptElementKind.interfaceElement:
+        return 'interface ' + node.getText()
+      case ts.ScriptElementKind.enumElement:
+        return 'enum ' + node.getText()
+      case ts.ScriptElementKind.enumMemberElement: {
+        let suffix = ''
+        const declaration = sym.declarations?.[0]
+        if (declaration && ts.isEnumMember(declaration)) {
+          const constantValue = this.checker.getConstantValue(declaration)
+          if (constantValue) {
+            suffix = ' = ' + constantValue.toString()
+          }
+        }
+        return '(enum member) ' + node.getText() + suffix
+      }
+      case ts.ScriptElementKind.functionElement:
+        return 'function ' + node.getText() + type()
+      case ts.ScriptElementKind.memberFunctionElement:
+        return '(method) ' + node.getText() + type()
+      case ts.ScriptElementKind.memberGetAccessorElement:
+        return 'get ' + node.getText() + ': ' + type()
+      case ts.ScriptElementKind.memberSetAccessorElement:
+        return 'set ' + node.getText() + type()
+      case ts.ScriptElementKind.constructorImplementationElement:
+        return ''
+    }
+    return node.getText() + ': ' + type()
+  }
 }
 
 function isAnonymousContainerOfSymbols(node: ts.Node): boolean {
@@ -343,3 +395,56 @@ function isAnonymousContainerOfSymbols(node: ts.Node): boolean {
     ts.isVariableDeclarationList(node)
   )
 }
+
+function scriptElementKind(
+  node: ts.Node,
+  sym: ts.Symbol
+): ts.ScriptElementKind {
+  const flags = sym.getFlags()
+  if (flags & ts.SymbolFlags.TypeAlias) {
+    return ts.ScriptElementKind.alias
+  }
+  if (flags & ts.SymbolFlags.Class) {
+    return ts.ScriptElementKind.classElement
+  }
+  if (flags & ts.SymbolFlags.Interface) {
+    return ts.ScriptElementKind.interfaceElement
+  }
+  if (flags & ts.SymbolFlags.Enum) {
+    return ts.ScriptElementKind.enumElement
+  }
+  if (flags & ts.SymbolFlags.EnumMember) {
+    return ts.ScriptElementKind.enumMemberElement
+  }
+  if (flags & ts.SymbolFlags.Method) {
+    return ts.ScriptElementKind.memberFunctionElement
+  }
+  if (flags & ts.SymbolFlags.GetAccessor) {
+    return ts.ScriptElementKind.memberGetAccessorElement
+  }
+  if (flags & ts.SymbolFlags.SetAccessor) {
+    return ts.ScriptElementKind.memberSetAccessorElement
+  }
+  if (flags & ts.SymbolFlags.Constructor) {
+    return ts.ScriptElementKind.constructorImplementationElement
+  }
+  if (flags & ts.SymbolFlags.Function) {
+    return ts.ScriptElementKind.functionElement
+  }
+  if (flags & ts.SymbolFlags.Variable) {
+    if (ts_inline.isParameter(sym)) {
+      return ts.ScriptElementKind.parameterElement
+    }
+    if (node.flags & ts.NodeFlags.Const) {
+      return ts.ScriptElementKind.constElement
+    }
+    if (node.flags & ts.NodeFlags.Let) {
+      return ts.ScriptElementKind.letElement
+    }
+    return ts.ScriptElementKind.variableElement
+  }
+  if (flags & ts.SymbolFlags.ClassMember) {
+    return ts.ScriptElementKind.memberVariableElement
+  }
+  return ts.ScriptElementKind.unknown
+}

src/TypeScriptInternal.ts

@@ -41,3 +41,17 @@ function isVariableDeclarationInitializedToBareOrAccessedRequire(
 function isVariableDeclaration(node: ts.Node): node is ts.VariableDeclaration {
   return node.kind === ts.SyntaxKind.VariableDeclaration
 }
+export function isParameter(sym: ts.Symbol): boolean {
+  // based on isFirstDeclarationOfSymbolParameter
+  const declaration = sym.declarations?.[0]
+  return !!ts.findAncestor(declaration, (node: ts.Node): boolean | 'quit' =>
+    ts.isParameter(node)
+      ? true
+      : ts.isBindingElement(node) ||
+        ts.isObjectBindingPattern(node) ||
+        ts.isArrayBindingPattern(node)
+      ? false
+      : 'quit'
+  )
+}
+