refactor: rewrite expression evaluation, fix #130

src/render/value.ts

@@ -0,0 +1,23 @@
+import { toValue } from '../util/underscore'
+import { Context } from '../context/context'
+import { parseLiteral } from '../parser/literal'
+
+export class Value {
+  private str: string
+
+  public constructor (str: string = '') {
+    this.str = str
+  }
+
+  public evaluate (ctx: Context) {
+    const literalValue = parseLiteral(this.str)
+    if (literalValue !== undefined) {
+      return literalValue
+    }
+    return ctx.get(this.str)
+  }
+
+  public value (ctx: Context) {
+    return toValue(this.evaluate(ctx))
+  }
+}