refactor(compiler): better constant hoist/stringify checks

packages/compiler-core/src/ast.ts

@@ -189,11 +189,23 @@ export interface DirectiveNode extends Node {
   parseResult?: ForParseResult
 }
 
+/**
+ * Static types have several levels.
+ * Higher levels implies lower levels. e.g. a node that can be stringified
+ * can always be hoisted and skipped for patch.
+ */
+export const enum ConstantTypes {
+  NOT_CONSTANT = 0,
+  CAN_SKIP_PATCH,
+  CAN_HOIST,
+  CAN_STRINGIFY
+}
+
 export interface SimpleExpressionNode extends Node {
   type: NodeTypes.SIMPLE_EXPRESSION
   content: string
   isStatic: boolean
-  isConstant: boolean
+  constType: ConstantTypes
   /**
    * Indicates this is an identifier for a hoist vnode call and points to the
    * hoisted node.
@@ -204,11 +216,6 @@ export interface SimpleExpressionNode extends Node {
    * the identifiers declared inside the function body.
    */
   identifiers?: string[]
-  /**
-   * some expressions (e.g. transformAssetUrls import identifiers) are constant,
-   * but cannot be stringified because they must be first evaluated at runtime.
-   */
-  isRuntimeConstant?: boolean
 }
 
 export interface InterpolationNode extends Node {
@@ -611,14 +618,14 @@ export function createSimpleExpression(
   content: SimpleExpressionNode['content'],
   isStatic: SimpleExpressionNode['isStatic'],
   loc: SourceLocation = locStub,
-  isConstant: boolean = false
+  constType: ConstantTypes = ConstantTypes.NOT_CONSTANT
 ): SimpleExpressionNode {
   return {
     type: NodeTypes.SIMPLE_EXPRESSION,
     loc,
-    isConstant,
     content,
-    isStatic
+    isStatic,
+    constType: isStatic ? ConstantTypes.CAN_STRINGIFY : constType
   }
 }