Adding Angular and dependent packages for testing

third_party/pkg/angular/lib/core/interpolate.dart

+part of angular.core;
+
+String _startSymbol = '{{';
+String _endSymbol = '}}';
+num _startSymbolLength = _startSymbol.length;
+num _endSymbolLength = _endSymbol.length;
+
+class Interpolation {
+  final String template;
+  final List<String> seperators;
+  final List<ParsedGetter> watchExpressions;
+  Function setter = (_) => _;
+
+  Interpolation(this.template, this.seperators, this.watchExpressions);
+
+  String call(List parts, [_, __]) {
+    var str = [];
+    for(var i = 0, ii = parts.length; i < ii; i++) {
+      str.add(seperators[i]);
+      var value = parts[i];
+      str.add(value == null ? '' : '$value');
+    }
+    str.add(seperators.last);
+    return setter(str.join(''));
+  }
+}
+
+/**
+ * Compiles a string with markup into an interpolation function. This service
+ * is used by the HTML [Compiler] service for data binding.
+ *
+ *
+ *     var $interpolate = ...; // injected
+ *     var exp = $interpolate('Hello {{name}}!');
+ *     expect(exp({name:'Angular'}).toEqual('Hello Angular!');
+ */
+@NgInjectableService()
+class Interpolate {
+  final Parser _parse;
+
+  Interpolate(this._parse);
+
+  /**
+   * Compile markup text into interpolation function.
+   *
+   * - `text`: The markup text to interpolate in form `foo {{expr}} bar`.
+   * - `mustHaveExpression`: if set to true then the interpolation string must
+   *      have embedded expression in order to return an interpolation function.
+   *      Strings with no embedded expression will return null for the
+   *      interpolation function.
+   */
+  Interpolation call(String template, [bool mustHaveExpression = false]) {
+    int startIndex;
+    int endIndex;
+    int index = 0;
+    int length = template.length;
+    bool hasInterpolation = false;
+    String exp;
+    List<String> separators = [];
+    List<ParsedGetter> watchExpressions = [];
+
+    while(index < length) {
+      if ( ((startIndex = template.indexOf(_startSymbol, index)) != -1) &&
+           ((endIndex = template.indexOf(_endSymbol, startIndex + _startSymbolLength)) != -1) ) {
+        separators.add(template.substring(index, startIndex));
+        exp = template.substring(startIndex + _startSymbolLength, endIndex);
+        watchExpressions.add((_parse(exp)..exp = exp).eval);
+        index = endIndex + _endSymbolLength;
+        hasInterpolation = true;
+      } else {
+        // we did not find anything, so we have to add the remainder to the chunks array
+        separators.add(template.substring(index));
+        index = length;
+      }
+    }
+    if (separators.length == watchExpressions.length) {
+      separators.add('');
+    }
+    if (!mustHaveExpression  || hasInterpolation) {
+      return new Interpolation(template, separators, watchExpressions);
+    }
+  }
+}