Function addInterceptor

test/angular/1.7/angular.js:17542–17588

(parsedExpression, interceptorFn)

    }

    function addInterceptor(parsedExpression, interceptorFn) {
      if (!interceptorFn) return parsedExpression;

      // Extract any existing interceptors out of the parsedExpression
      // to ensure the original parsedExpression is always the $$intercepted
      if (parsedExpression.$$interceptor) {
        interceptorFn = chainInterceptors(parsedExpression.$$interceptor, interceptorFn);
        parsedExpression = parsedExpression.$$intercepted;
      }

      var useInputs = false;

      var fn = function interceptedExpression(scope, locals, assign, inputs) {
        var value = useInputs && inputs ? inputs[0] : parsedExpression(scope, locals, assign, inputs);
        return interceptorFn(value);
      };

      // Maintain references to the interceptor/intercepted
      fn.$$intercepted = parsedExpression;
      fn.$$interceptor = interceptorFn;

      // Propogate the literal/oneTime/constant attributes
      fn.literal = parsedExpression.literal;
      fn.oneTime = parsedExpression.oneTime;
      fn.constant = parsedExpression.constant;

      // Treat the interceptor like filters.
      // If it is not $stateful then only watch its inputs.
      // If the expression itself has no inputs then use the full expression as an input.
      if (!interceptorFn.$stateful) {
        useInputs = !parsedExpression.inputs;
        fn.inputs = parsedExpression.inputs ? parsedExpression.inputs : [parsedExpression];

        if (!interceptorFn.$$pure) {
          fn.inputs = fn.inputs.map(function(e) {
              // Remove the isPure flag of inputs when it is not absolute because they are now wrapped in a
              // non-pure interceptor function.
              if (e.isPure === PURITY_RELATIVE) {
                return function depurifier(s) { return e(s); };
              }
              return e;
            });
        }
      }

      return addWatchDelegate(fn);
    }
  }];
}