refactor: rewrite expression evaluation, fix #130

src/render/operator.ts

@@ -0,0 +1,59 @@
+import { isComparable } from '../drop/icomparable'
+import { isFunction } from '../util/underscore'
+import { isTruthy } from '../render/boolean'
+
+export const precedence = {
+  '==': 1,
+  '!=': 1,
+  '>': 1,
+  '<': 1,
+  '>=': 1,
+  '<=': 1,
+  'contains': 1,
+  'and': 0,
+  'or': 0
+}
+
+export const operatorImpls: {[key: string]: (lhs: any, rhs: any) => boolean} = {
+  '==': (l: any, r: any) => {
+    if (isComparable(l)) return l.equals(r)
+    if (isComparable(r)) return r.equals(l)
+    return l === r
+  },
+  '!=': (l: any, r: any) => {
+    if (isComparable(l)) return !l.equals(r)
+    if (isComparable(r)) return !r.equals(l)
+    return l !== r
+  },
+  '>': (l: any, r: any) => {
+    if (isComparable(l)) return l.gt(r)
+    if (isComparable(r)) return r.lt(l)
+    return l > r
+  },
+  '<': (l: any, r: any) => {
+    if (isComparable(l)) return l.lt(r)
+    if (isComparable(r)) return r.gt(l)
+    return l < r
+  },
+  '>=': (l: any, r: any) => {
+    if (isComparable(l)) return l.geq(r)
+    if (isComparable(r)) return r.leq(l)
+    return l >= r
+  },
+  '<=': (l: any, r: any) => {
+    if (isComparable(l)) return l.leq(r)
+    if (isComparable(r)) return r.geq(l)
+    return l <= r
+  },
+  'contains': (l: any, r: any) => {
+    return l && isFunction(l.indexOf) ? l.indexOf(r) > -1 : false
+  },
+  'and': (l: any, r: any) => isTruthy(l) && isTruthy(r),
+  'or': (l: any, r: any) => isTruthy(l) || isTruthy(r)
+}
+
+const list = Object.keys(precedence)
+
+export function isOperator (token: string) {
+  return list.includes(token)
+}