refactor: move angular source to /packages rather than modules/@angular

packages/compiler/src/ml_parser/icu_ast_expander.ts

@@ -0,0 +1,125 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {ParseError, ParseSourceSpan} from '../parse_util';
+
+import * as html from './ast';
+
+// http://cldr.unicode.org/index/cldr-spec/plural-rules
+const PLURAL_CASES: string[] = ['zero', 'one', 'two', 'few', 'many', 'other'];
+
+/**
+ * Expands special forms into elements.
+ *
+ * For example,
+ *
+ * ```
+ * { messages.length, plural,
+ *   =0 {zero}
+ *   =1 {one}
+ *   other {more than one}
+ * }
+ * ```
+ *
+ * will be expanded into
+ *
+ * ```
+ * <ng-container [ngPlural]="messages.length">
+ *   <ng-template ngPluralCase="=0">zero</ng-template>
+ *   <ng-template ngPluralCase="=1">one</ng-template>
+ *   <ng-template ngPluralCase="other">more than one</ng-template>
+ * </ng-container>
+ * ```
+ */
+export function expandNodes(nodes: html.Node[]): ExpansionResult {
+  const expander = new _Expander();
+  return new ExpansionResult(html.visitAll(expander, nodes), expander.isExpanded, expander.errors);
+}
+
+export class ExpansionResult {
+  constructor(public nodes: html.Node[], public expanded: boolean, public errors: ParseError[]) {}
+}
+
+export class ExpansionError extends ParseError {
+  constructor(span: ParseSourceSpan, errorMsg: string) { super(span, errorMsg); }
+}
+
+/**
+ * Expand expansion forms (plural, select) to directives
+ *
+ * @internal
+ */
+class _Expander implements html.Visitor {
+  isExpanded: boolean = false;
+  errors: ParseError[] = [];
+
+  visitElement(element: html.Element, context: any): any {
+    return new html.Element(
+        element.name, element.attrs, html.visitAll(this, element.children), element.sourceSpan,
+        element.startSourceSpan, element.endSourceSpan);
+  }
+
+  visitAttribute(attribute: html.Attribute, context: any): any { return attribute; }
+
+  visitText(text: html.Text, context: any): any { return text; }
+
+  visitComment(comment: html.Comment, context: any): any { return comment; }
+
+  visitExpansion(icu: html.Expansion, context: any): any {
+    this.isExpanded = true;
+    return icu.type == 'plural' ? _expandPluralForm(icu, this.errors) :
+                                  _expandDefaultForm(icu, this.errors);
+  }
+
+  visitExpansionCase(icuCase: html.ExpansionCase, context: any): any {
+    throw new Error('Should not be reached');
+  }
+}
+
+// Plural forms are expanded to `NgPlural` and `NgPluralCase`s
+function _expandPluralForm(ast: html.Expansion, errors: ParseError[]): html.Element {
+  const children = ast.cases.map(c => {
+    if (PLURAL_CASES.indexOf(c.value) == -1 && !c.value.match(/^=\d+$/)) {
+      errors.push(new ExpansionError(
+          c.valueSourceSpan,
+          `Plural cases should be "=<number>" or one of ${PLURAL_CASES.join(", ")}`));
+    }
+
+    const expansionResult = expandNodes(c.expression);
+    errors.push(...expansionResult.errors);
+
+    return new html.Element(
+        `ng-template`, [new html.Attribute('ngPluralCase', `${c.value}`, c.valueSourceSpan)],
+        expansionResult.nodes, c.sourceSpan, c.sourceSpan, c.sourceSpan);
+  });
+  const switchAttr = new html.Attribute('[ngPlural]', ast.switchValue, ast.switchValueSourceSpan);
+  return new html.Element(
+      'ng-container', [switchAttr], children, ast.sourceSpan, ast.sourceSpan, ast.sourceSpan);
+}
+
+// ICU messages (excluding plural form) are expanded to `NgSwitch`  and `NgSwitychCase`s
+function _expandDefaultForm(ast: html.Expansion, errors: ParseError[]): html.Element {
+  const children = ast.cases.map(c => {
+    const expansionResult = expandNodes(c.expression);
+    errors.push(...expansionResult.errors);
+
+    if (c.value === 'other') {
+      // other is the default case when no values match
+      return new html.Element(
+          `ng-template`, [new html.Attribute('ngSwitchDefault', '', c.valueSourceSpan)],
+          expansionResult.nodes, c.sourceSpan, c.sourceSpan, c.sourceSpan);
+    }
+
+    return new html.Element(
+        `ng-template`, [new html.Attribute('ngSwitchCase', `${c.value}`, c.valueSourceSpan)],
+        expansionResult.nodes, c.sourceSpan, c.sourceSpan, c.sourceSpan);
+  });
+  const switchAttr = new html.Attribute('[ngSwitch]', ast.switchValue, ast.switchValueSourceSpan);
+  return new html.Element(
+      'ng-container', [switchAttr], children, ast.sourceSpan, ast.sourceSpan, ast.sourceSpan);
+}