sdk/lib/_internal/compiler/implementation/js_emitter/nsm_emitter.dart - sdk.git - Git at Google

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 part of dart2js.js_emitter;

 class NsmEmitter extends CodeEmitterHelper {
   final List<Selector> trivialNsmHandlers = <Selector>[];

   /// If this is true then we can generate the noSuchMethod handlers at startup
   /// time, instead of them being emitted as part of the Object class.
   bool get generateTrivialNsmHandlers => true;

   // If we need fewer than this many noSuchMethod handlers we can save space by
   // just emitting them in JS, rather than emitting the JS needed to generate
   // them at run time.
   static const VERY_FEW_NO_SUCH_METHOD_HANDLERS = 10;

   static const MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING = 4;

   void emitNoSuchMethodHandlers(DefineStubFunction defineStub) {
     // Do not generate no such method handlers if there is no class.
     if (compiler.codegenWorld.instantiatedClasses.isEmpty) return;

     String noSuchMethodName = namer.publicInstanceMethodNameByArity(
         Compiler.NO_SUCH_METHOD, Compiler.NO_SUCH_METHOD_ARG_COUNT);

     // Keep track of the JavaScript names we've already added so we
     // do not introduce duplicates (bad for code size).
     Map<String, Selector> addedJsNames = new Map<String, Selector>();

     void addNoSuchMethodHandlers(SourceString ignore, Set<Selector> selectors) {
       // Cache the object class and type.
       ClassElement objectClass = compiler.objectClass;
       DartType objectType = objectClass.computeType(compiler);

       for (Selector selector in selectors) {
         TypeMask mask = selector.mask;
         if (mask == null) {
           mask = new TypeMask.subclass(compiler.objectClass);
         }

         if (!mask.needsNoSuchMethodHandling(selector, compiler)) continue;
         String jsName = namer.invocationMirrorInternalName(selector);
         addedJsNames[jsName] = selector;
         String reflectionName = task.getReflectionName(selector, jsName);
         if (reflectionName != null) {
           task.mangledFieldNames[jsName] = reflectionName;
         }
       }
     }

     compiler.codegenWorld.invokedNames.forEach(addNoSuchMethodHandlers);
     compiler.codegenWorld.invokedGetters.forEach(addNoSuchMethodHandlers);
     compiler.codegenWorld.invokedSetters.forEach(addNoSuchMethodHandlers);

     // Set flag used by generateMethod helper below.  If we have very few
     // handlers we use defineStub for them all, rather than try to generate them
     // at runtime.
     bool haveVeryFewNoSuchMemberHandlers =
         (addedJsNames.length < VERY_FEW_NO_SUCH_METHOD_HANDLERS);

     jsAst.Expression generateMethod(String jsName, Selector selector) {
       // Values match JSInvocationMirror in js-helper library.
       int type = selector.invocationMirrorKind;
       List<jsAst.Parameter> parameters = <jsAst.Parameter>[];
       CodeBuffer args = new CodeBuffer();
       for (int i = 0; i < selector.argumentCount; i++) {
         parameters.add(new jsAst.Parameter('\$$i'));
       }

       List<jsAst.Expression> argNames =
           selector.getOrderedNamedArguments().map((SourceString name) =>
               js.string(name.slowToString())).toList();

       String methodName = selector.invocationMirrorMemberName;
       String internalName = namer.invocationMirrorInternalName(selector);
       String reflectionName = task.getReflectionName(selector, internalName);
       if (!haveVeryFewNoSuchMemberHandlers &&
           isTrivialNsmHandler(type, argNames, selector, internalName) &&
           reflectionName == null) {
         trivialNsmHandlers.add(selector);
         return null;
       }

       assert(backend.isInterceptedName(Compiler.NO_SUCH_METHOD));
       jsAst.Expression expression = js('this.$noSuchMethodName')(
           [js('this'),
            namer.elementAccess(backend.getCreateInvocationMirror())([
                js.string(compiler.enableMinification ?
                          internalName : methodName),
                js.string(internalName),
                type,
                new jsAst.ArrayInitializer.from(
                    parameters.map((param) => js(param.name)).toList()),
                new jsAst.ArrayInitializer.from(argNames)])]);
       parameters = backend.isInterceptedName(selector.name)
           ? ([new jsAst.Parameter('\$receiver')]..addAll(parameters))
           : parameters;
       return js.fun(parameters, js.return_(expression));
     }

     for (String jsName in addedJsNames.keys.toList()..sort()) {
       Selector selector = addedJsNames[jsName];
       jsAst.Expression method = generateMethod(jsName, selector);
       if (method != null) {
         defineStub(jsName, method);
         String reflectionName = task.getReflectionName(selector, jsName);
         if (reflectionName != null) {
           bool accessible = compiler.world.allFunctions.filter(selector).any(
               (Element e) => backend.isAccessibleByReflection(e));
           defineStub('+$reflectionName', js(accessible ? '1' : '0'));
         }
       }
     }
   }

   // Identify the noSuchMethod handlers that are so simple that we can
   // generate them programatically.
   bool isTrivialNsmHandler(
       int type, List argNames, Selector selector, String internalName) {
     if (!generateTrivialNsmHandlers) return false;
     // Check for interceptor calling convention.
     if (backend.isInterceptedName(selector.name)) {
       // We can handle the calling convention used by intercepted names in the
       // diff encoding, but we don't use that for non-minified code.
       if (!compiler.enableMinification) return false;
       String shortName = namer.invocationMirrorInternalName(selector);
       if (shortName.length > MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING) {
         return false;
       }
     }
     // Check for named arguments.
     if (argNames.length != 0) return false;
     // Check for unexpected name (this doesn't really happen).
     if (internalName.startsWith(namer.getterPrefix[0])) return type == 1;
     if (internalName.startsWith(namer.setterPrefix[0])) return type == 2;
     return type == 0;
   }

   /**
    * Adds (at runtime) the handlers to the Object class which catch calls to
    * methods that the object does not have.  The handlers create an invocation
    * mirror object.
    *
    * The current version only gives you the minified name when minifying (when
    * not minifying this method is not called).
    *
    * In order to generate the noSuchMethod handlers we only need the minified
    * name of the method.  We test the first character of the minified name to
    * determine if it is a getter or a setter, and we use the arguments array at
    * runtime to get the number of arguments and their values.  If the method
    * involves named arguments etc. then we don't handle it here, but emit the
    * handler method directly on the Object class.
    *
    * The minified names are mostly 1-4 character names, which we emit in sorted
    * order (primary key is length, secondary ordering is lexicographic).  This
    * gives an order like ... dD dI dX da ...
    *
    * Gzip is good with repeated text, but it can't diff-encode, so we do that
    * for it.  We encode the minified names in a comma-separated string, but all
    * the 1-4 character names are encoded before the first comma as a series of
    * base 26 numbers.  The last digit of each number is lower case, the others
    * are upper case, so 1 is "b" and 26 is "Ba".
    *
    * We think of the minified names as base 88 numbers using the ASCII
    * characters from # to z.  The base 26 numbers each encode the delta from
    * the previous minified name to the next.  So if there is a minified name
    * called Df and the next is Dh, then they are 2971 and 2973 when thought of
    * as base 88 numbers.  The difference is 2, which is "c" in lower-case-
    * terminated base 26.
    *
    * The reason we don't encode long minified names with this method is that
    * decoding the base 88 numbers would overflow JavaScript's puny integers.
    *
    * There are some selectors that have a special calling convention (because
    * they are called with the receiver as the first argument).  They need a
    * slightly different noSuchMethod handler, so we handle these first.
    */
   void addTrivialNsmHandlers(List<jsAst.Node> statements) {
     if (trivialNsmHandlers.length == 0) return;
     // Sort by calling convention, JS name length and by JS name.
     trivialNsmHandlers.sort((a, b) {
       bool aIsIntercepted = backend.isInterceptedName(a.name);
       bool bIsIntercepted = backend.isInterceptedName(b.name);
       if (aIsIntercepted != bIsIntercepted) return aIsIntercepted ? -1 : 1;
       String aName = namer.invocationMirrorInternalName(a);
       String bName = namer.invocationMirrorInternalName(b);
       if (aName.length != bName.length) return aName.length - bName.length;
       return aName.compareTo(bName);
     });

     // Find out how many selectors there are with the special calling
     // convention.
     int firstNormalSelector = trivialNsmHandlers.length;
     for (int i = 0; i < trivialNsmHandlers.length; i++) {
       if (!backend.isInterceptedName(trivialNsmHandlers[i].name)) {
         firstNormalSelector = i;
         break;
       }
     }

     // Get the short names (JS names, perhaps minified).
     Iterable<String> shorts = trivialNsmHandlers.map((selector) =>
          namer.invocationMirrorInternalName(selector));
     final diffShorts = <String>[];
     var diffEncoding = new StringBuffer();

     // Treat string as a number in base 88 with digits in ASCII order from # to
     // z.  The short name sorting is based on length, and uses ASCII order for
     // equal length strings so this means that names are ascending.  The hash
     // character, #, is never given as input, but we need it because it's the
     // implicit leading zero (otherwise we could not code names with leading
     // dollar signs).
     int fromBase88(String x) {
       int answer = 0;
       for (int i = 0; i < x.length; i++) {
         int c = x.codeUnitAt(i);
         // No support for Unicode minified identifiers in JS.
         assert(c >= $$ && c <= $z);
         answer *= 88;
         answer += c - $HASH;
       }
       return answer;
     }

     // Big endian encoding, A = 0, B = 1...
     // A lower case letter terminates the number.
     String toBase26(int x) {
       int c = x;
       var encodingChars = <int>[];
       encodingChars.add($a + (c % 26));
       while (true) {
         c ~/= 26;
         if (c == 0) break;
         encodingChars.add($A + (c % 26));
       }
       return new String.fromCharCodes(encodingChars.reversed.toList());
     }

     bool minify = compiler.enableMinification;
     bool useDiffEncoding = minify && shorts.length > 30;

     int previous = 0;
     int nameCounter = 0;
     for (String short in shorts) {
       // Emit period that resets the diff base to zero when we switch to normal
       // calling convention (this avoids the need to code negative diffs).
       if (useDiffEncoding && nameCounter == firstNormalSelector) {
         diffEncoding.write(".");
         previous = 0;
       }
       if (short.length <= MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING &&
           useDiffEncoding) {
         int base63 = fromBase88(short);
         int diff = base63 - previous;
         previous = base63;
         String base26Diff = toBase26(diff);
         diffEncoding.write(base26Diff);
       } else {
         if (useDiffEncoding || diffEncoding.length != 0) {
           diffEncoding.write(",");
         }
         diffEncoding.write(short);
       }
       nameCounter++;
     }

     // Startup code that loops over the method names and puts handlers on the
     // Object class to catch noSuchMethod invocations.
     ClassElement objectClass = compiler.objectClass;
     String createInvocationMirror = namer.isolateAccess(
         backend.getCreateInvocationMirror());
     String noSuchMethodName = namer.publicInstanceMethodNameByArity(
         Compiler.NO_SUCH_METHOD, Compiler.NO_SUCH_METHOD_ARG_COUNT);
     var type = 0;
     if (useDiffEncoding) {
       statements.addAll([
         js('var objectClassObject = '
            '        collectedClasses["${namer.getNameOfClass(objectClass)}"],'
            '    shortNames = "$diffEncoding".split(","),'
            '    nameNumber = 0,'
            '    diffEncodedString = shortNames[0],'
            '    calculatedShortNames = [0, 1]'),  // 0, 1 are args for splice.
         js.if_('objectClassObject instanceof Array',
                js('objectClassObject = objectClassObject[1]')),
         js.for_('var i = 0', 'i < diffEncodedString.length', 'i++', [
           js('var codes = [],'
              '    diff = 0,'
              '    digit = diffEncodedString.charCodeAt(i)'),
           js.if_('digit == ${$PERIOD}', [
             js('nameNumber = 0'),
             js('digit = diffEncodedString.charCodeAt(++i)')
           ]),
           js.while_('digit <= ${$Z}', [
             js('diff *= 26'),
             js('diff += (digit - ${$A})'),
             js('digit = diffEncodedString.charCodeAt(++i)')
           ]),
           js('diff *= 26'),
           js('diff += (digit - ${$a})'),
           js('nameNumber += diff'),
           js.for_('var remaining = nameNumber',
                   'remaining > 0',
                   'remaining = (remaining / 88) | 0', [
             js('codes.unshift(${$HASH} + remaining % 88)')
           ]),
           js('calculatedShortNames.push('
              '    String.fromCharCode.apply(String, codes))')
         ]),
         js('shortNames.splice.apply(shortNames, calculatedShortNames)')
       ]);
     } else {
       // No useDiffEncoding version.
       Iterable<String> longs = trivialNsmHandlers.map((selector) =>
              selector.invocationMirrorMemberName);
       String longNamesConstant = minify ? "" :
           ',longNames = "${longs.join(",")}".split(",")';
       statements.add(
         js('var objectClassObject = '
            '        collectedClasses["${namer.getNameOfClass(objectClass)}"],'
            '    shortNames = "$diffEncoding".split(",")'
            '    $longNamesConstant'));
       statements.add(
           js.if_('objectClassObject instanceof Array',
                  js('objectClassObject = objectClassObject[1]')));
     }

     String sliceOffset = ', (j < $firstNormalSelector) ? 1 : 0';
     if (firstNormalSelector == 0) sliceOffset = '';
     if (firstNormalSelector == shorts.length) sliceOffset = ', 1';

     String whatToPatch = task.nativeEmitter.handleNoSuchMethod ?
                          "Object.prototype" :
                          "objectClassObject";

     var params = ['name', 'short', 'type'];
     var sliceOffsetParam = '';
     var slice = 'Array.prototype.slice.call';
     if (!sliceOffset.isEmpty) {
       sliceOffsetParam = ', sliceOffset';
       params.add('sliceOffset');
     }
     statements.addAll([
       js.for_('var j = 0', 'j < shortNames.length', 'j++', [
         js('var type = 0'),
         js('var short = shortNames[j]'),
         js.if_('short[0] == "${namer.getterPrefix[0]}"', js('type = 1')),
         js.if_('short[0] == "${namer.setterPrefix[0]}"', js('type = 2')),
         // Generate call to:
         // createInvocationMirror(String name, internalName, type, arguments,
         //                        argumentNames)
         js('$whatToPatch[short] = #(${minify ? "shortNames" : "longNames"}[j], '
                                     'short, type$sliceOffset)',
            js.fun(params, [js.return_(js.fun([],
                [js.return_(js(
                    'this.$noSuchMethodName('
                        'this, '
                        '$createInvocationMirror('
                            'name, short, type, '
                            '$slice(arguments$sliceOffsetParam), []))'))]))]))
       ])
     ]);
   }
 }
	// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	part of dart2js.js_emitter;

	class NsmEmitter extends CodeEmitterHelper {
	final List<Selector> trivialNsmHandlers = <Selector>[];

	/// If this is true then we can generate the noSuchMethod handlers at startup
	/// time, instead of them being emitted as part of the Object class.
	bool get generateTrivialNsmHandlers => true;

	// If we need fewer than this many noSuchMethod handlers we can save space by
	// just emitting them in JS, rather than emitting the JS needed to generate
	// them at run time.
	static const VERY_FEW_NO_SUCH_METHOD_HANDLERS = 10;

	static const MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING = 4;

	void emitNoSuchMethodHandlers(DefineStubFunction defineStub) {
	// Do not generate no such method handlers if there is no class.
	if (compiler.codegenWorld.instantiatedClasses.isEmpty) return;

	String noSuchMethodName = namer.publicInstanceMethodNameByArity(
	Compiler.NO_SUCH_METHOD, Compiler.NO_SUCH_METHOD_ARG_COUNT);

	// Keep track of the JavaScript names we've already added so we
	// do not introduce duplicates (bad for code size).
	Map<String, Selector> addedJsNames = new Map<String, Selector>();

	void addNoSuchMethodHandlers(SourceString ignore, Set<Selector> selectors) {
	// Cache the object class and type.
	ClassElement objectClass = compiler.objectClass;
	DartType objectType = objectClass.computeType(compiler);

	for (Selector selector in selectors) {
	TypeMask mask = selector.mask;
	if (mask == null) {
	mask = new TypeMask.subclass(compiler.objectClass);
	}

	if (!mask.needsNoSuchMethodHandling(selector, compiler)) continue;
	String jsName = namer.invocationMirrorInternalName(selector);
	addedJsNames[jsName] = selector;
	String reflectionName = task.getReflectionName(selector, jsName);
	if (reflectionName != null) {
	task.mangledFieldNames[jsName] = reflectionName;
	}
	}
	}

	compiler.codegenWorld.invokedNames.forEach(addNoSuchMethodHandlers);
	compiler.codegenWorld.invokedGetters.forEach(addNoSuchMethodHandlers);
	compiler.codegenWorld.invokedSetters.forEach(addNoSuchMethodHandlers);

	// Set flag used by generateMethod helper below. If we have very few
	// handlers we use defineStub for them all, rather than try to generate them
	// at runtime.
	bool haveVeryFewNoSuchMemberHandlers =
	(addedJsNames.length < VERY_FEW_NO_SUCH_METHOD_HANDLERS);

	jsAst.Expression generateMethod(String jsName, Selector selector) {
	// Values match JSInvocationMirror in js-helper library.
	int type = selector.invocationMirrorKind;
	List<jsAst.Parameter> parameters = <jsAst.Parameter>[];
	CodeBuffer args = new CodeBuffer();
	for (int i = 0; i < selector.argumentCount; i++) {
	parameters.add(new jsAst.Parameter('\$$i'));
	}

	List<jsAst.Expression> argNames =
	selector.getOrderedNamedArguments().map((SourceString name) =>
	js.string(name.slowToString())).toList();

	String methodName = selector.invocationMirrorMemberName;
	String internalName = namer.invocationMirrorInternalName(selector);
	String reflectionName = task.getReflectionName(selector, internalName);
	if (!haveVeryFewNoSuchMemberHandlers &&
	isTrivialNsmHandler(type, argNames, selector, internalName) &&
	reflectionName == null) {
	trivialNsmHandlers.add(selector);
	return null;
	}

	assert(backend.isInterceptedName(Compiler.NO_SUCH_METHOD));
	jsAst.Expression expression = js('this.$noSuchMethodName')(
	[js('this'),
	namer.elementAccess(backend.getCreateInvocationMirror())([
	js.string(compiler.enableMinification ?
	internalName : methodName),
	js.string(internalName),
	type,
	new jsAst.ArrayInitializer.from(
	parameters.map((param) => js(param.name)).toList()),
	new jsAst.ArrayInitializer.from(argNames)])]);
	parameters = backend.isInterceptedName(selector.name)
	? ([new jsAst.Parameter('\$receiver')]..addAll(parameters))
	: parameters;
	return js.fun(parameters, js.return_(expression));
	}

	for (String jsName in addedJsNames.keys.toList()..sort()) {
	Selector selector = addedJsNames[jsName];
	jsAst.Expression method = generateMethod(jsName, selector);
	if (method != null) {
	defineStub(jsName, method);
	String reflectionName = task.getReflectionName(selector, jsName);
	if (reflectionName != null) {
	bool accessible = compiler.world.allFunctions.filter(selector).any(
	(Element e) => backend.isAccessibleByReflection(e));
	defineStub('+$reflectionName', js(accessible ? '1' : '0'));
	}
	}
	}
	}

	// Identify the noSuchMethod handlers that are so simple that we can
	// generate them programatically.
	bool isTrivialNsmHandler(
	int type, List argNames, Selector selector, String internalName) {
	if (!generateTrivialNsmHandlers) return false;
	// Check for interceptor calling convention.
	if (backend.isInterceptedName(selector.name)) {
	// We can handle the calling convention used by intercepted names in the
	// diff encoding, but we don't use that for non-minified code.
	if (!compiler.enableMinification) return false;
	String shortName = namer.invocationMirrorInternalName(selector);
	if (shortName.length > MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING) {
	return false;
	}
	}
	// Check for named arguments.
	if (argNames.length != 0) return false;
	// Check for unexpected name (this doesn't really happen).
	if (internalName.startsWith(namer.getterPrefix[0])) return type == 1;
	if (internalName.startsWith(namer.setterPrefix[0])) return type == 2;
	return type == 0;
	}

	/**
	* Adds (at runtime) the handlers to the Object class which catch calls to
	* methods that the object does not have. The handlers create an invocation
	* mirror object.
	*
	* The current version only gives you the minified name when minifying (when
	* not minifying this method is not called).
	*
	* In order to generate the noSuchMethod handlers we only need the minified
	* name of the method. We test the first character of the minified name to
	* determine if it is a getter or a setter, and we use the arguments array at
	* runtime to get the number of arguments and their values. If the method
	* involves named arguments etc. then we don't handle it here, but emit the
	* handler method directly on the Object class.
	*
	* The minified names are mostly 1-4 character names, which we emit in sorted
	* order (primary key is length, secondary ordering is lexicographic). This
	* gives an order like ... dD dI dX da ...
	*
	* Gzip is good with repeated text, but it can't diff-encode, so we do that
	* for it. We encode the minified names in a comma-separated string, but all
	* the 1-4 character names are encoded before the first comma as a series of
	* base 26 numbers. The last digit of each number is lower case, the others
	* are upper case, so 1 is "b" and 26 is "Ba".
	*
	* We think of the minified names as base 88 numbers using the ASCII
	* characters from # to z. The base 26 numbers each encode the delta from
	* the previous minified name to the next. So if there is a minified name
	* called Df and the next is Dh, then they are 2971 and 2973 when thought of
	* as base 88 numbers. The difference is 2, which is "c" in lower-case-
	* terminated base 26.
	*
	* The reason we don't encode long minified names with this method is that
	* decoding the base 88 numbers would overflow JavaScript's puny integers.
	*
	* There are some selectors that have a special calling convention (because
	* they are called with the receiver as the first argument). They need a
	* slightly different noSuchMethod handler, so we handle these first.
	*/
	void addTrivialNsmHandlers(List<jsAst.Node> statements) {
	if (trivialNsmHandlers.length == 0) return;
	// Sort by calling convention, JS name length and by JS name.
	trivialNsmHandlers.sort((a, b) {
	bool aIsIntercepted = backend.isInterceptedName(a.name);
	bool bIsIntercepted = backend.isInterceptedName(b.name);
	if (aIsIntercepted != bIsIntercepted) return aIsIntercepted ? -1 : 1;
	String aName = namer.invocationMirrorInternalName(a);
	String bName = namer.invocationMirrorInternalName(b);
	if (aName.length != bName.length) return aName.length - bName.length;
	return aName.compareTo(bName);
	});

	// Find out how many selectors there are with the special calling
	// convention.
	int firstNormalSelector = trivialNsmHandlers.length;
	for (int i = 0; i < trivialNsmHandlers.length; i++) {
	if (!backend.isInterceptedName(trivialNsmHandlers[i].name)) {
	firstNormalSelector = i;
	break;
	}
	}

	// Get the short names (JS names, perhaps minified).
	Iterable<String> shorts = trivialNsmHandlers.map((selector) =>
	namer.invocationMirrorInternalName(selector));
	final diffShorts = <String>[];
	var diffEncoding = new StringBuffer();

	// Treat string as a number in base 88 with digits in ASCII order from # to
	// z. The short name sorting is based on length, and uses ASCII order for
	// equal length strings so this means that names are ascending. The hash
	// character, #, is never given as input, but we need it because it's the
	// implicit leading zero (otherwise we could not code names with leading
	// dollar signs).
	int fromBase88(String x) {
	int answer = 0;
	for (int i = 0; i < x.length; i++) {
	int c = x.codeUnitAt(i);
	// No support for Unicode minified identifiers in JS.
	assert(c >= $$ && c <= $z);
	answer *= 88;
	answer += c - $HASH;
	}
	return answer;
	}

	// Big endian encoding, A = 0, B = 1...
	// A lower case letter terminates the number.
	String toBase26(int x) {
	int c = x;
	var encodingChars = <int>[];
	encodingChars.add($a + (c % 26));
	while (true) {
	c ~/= 26;
	if (c == 0) break;
	encodingChars.add($A + (c % 26));
	}
	return new String.fromCharCodes(encodingChars.reversed.toList());
	}

	bool minify = compiler.enableMinification;
	bool useDiffEncoding = minify && shorts.length > 30;

	int previous = 0;
	int nameCounter = 0;
	for (String short in shorts) {
	// Emit period that resets the diff base to zero when we switch to normal
	// calling convention (this avoids the need to code negative diffs).
	if (useDiffEncoding && nameCounter == firstNormalSelector) {
	diffEncoding.write(".");
	previous = 0;
	}
	if (short.length <= MAX_MINIFIED_LENGTH_FOR_DIFF_ENCODING &&
	useDiffEncoding) {
	int base63 = fromBase88(short);
	int diff = base63 - previous;
	previous = base63;
	String base26Diff = toBase26(diff);
	diffEncoding.write(base26Diff);
	} else {
	if (useDiffEncoding \|\| diffEncoding.length != 0) {
	diffEncoding.write(",");
	}
	diffEncoding.write(short);
	}
	nameCounter++;
	}

	// Startup code that loops over the method names and puts handlers on the
	// Object class to catch noSuchMethod invocations.
	ClassElement objectClass = compiler.objectClass;
	String createInvocationMirror = namer.isolateAccess(
	backend.getCreateInvocationMirror());
	String noSuchMethodName = namer.publicInstanceMethodNameByArity(
	Compiler.NO_SUCH_METHOD, Compiler.NO_SUCH_METHOD_ARG_COUNT);
	var type = 0;
	if (useDiffEncoding) {
	statements.addAll([
	js('var objectClassObject = '
	' collectedClasses["${namer.getNameOfClass(objectClass)}"],'
	' shortNames = "$diffEncoding".split(","),'
	' nameNumber = 0,'
	' diffEncodedString = shortNames[0],'
	' calculatedShortNames = [0, 1]'), // 0, 1 are args for splice.
	js.if_('objectClassObject instanceof Array',
	js('objectClassObject = objectClassObject[1]')),
	js.for_('var i = 0', 'i < diffEncodedString.length', 'i++', [
	js('var codes = [],'
	' diff = 0,'
	' digit = diffEncodedString.charCodeAt(i)'),
	js.if_('digit == ${$PERIOD}', [
	js('nameNumber = 0'),
	js('digit = diffEncodedString.charCodeAt(++i)')
	]),
	js.while_('digit <= ${$Z}', [
	js('diff *= 26'),
	js('diff += (digit - ${$A})'),
	js('digit = diffEncodedString.charCodeAt(++i)')
	]),
	js('diff *= 26'),
	js('diff += (digit - ${$a})'),
	js('nameNumber += diff'),
	js.for_('var remaining = nameNumber',
	'remaining > 0',
	'remaining = (remaining / 88) \| 0', [
	js('codes.unshift(${$HASH} + remaining % 88)')
	]),
	js('calculatedShortNames.push('
	' String.fromCharCode.apply(String, codes))')
	]),
	js('shortNames.splice.apply(shortNames, calculatedShortNames)')
	]);
	} else {
	// No useDiffEncoding version.
	Iterable<String> longs = trivialNsmHandlers.map((selector) =>
	selector.invocationMirrorMemberName);
	String longNamesConstant = minify ? "" :
	',longNames = "${longs.join(",")}".split(",")';
	statements.add(
	js('var objectClassObject = '
	' collectedClasses["${namer.getNameOfClass(objectClass)}"],'
	' shortNames = "$diffEncoding".split(",")'
	' $longNamesConstant'));
	statements.add(
	js.if_('objectClassObject instanceof Array',
	js('objectClassObject = objectClassObject[1]')));
	}

	String sliceOffset = ', (j < $firstNormalSelector) ? 1 : 0';
	if (firstNormalSelector == 0) sliceOffset = '';
	if (firstNormalSelector == shorts.length) sliceOffset = ', 1';

	String whatToPatch = task.nativeEmitter.handleNoSuchMethod ?
	"Object.prototype" :
	"objectClassObject";

	var params = ['name', 'short', 'type'];
	var sliceOffsetParam = '';
	var slice = 'Array.prototype.slice.call';
	if (!sliceOffset.isEmpty) {
	sliceOffsetParam = ', sliceOffset';
	params.add('sliceOffset');
	}
	statements.addAll([
	js.for_('var j = 0', 'j < shortNames.length', 'j++', [
	js('var type = 0'),
	js('var short = shortNames[j]'),
	js.if_('short[0] == "${namer.getterPrefix[0]}"', js('type = 1')),
	js.if_('short[0] == "${namer.setterPrefix[0]}"', js('type = 2')),
	// Generate call to:
	// createInvocationMirror(String name, internalName, type, arguments,
	// argumentNames)
	js('$whatToPatch[short] = #(${minify ? "shortNames" : "longNames"}[j], '
	'short, type$sliceOffset)',
	js.fun(params, [js.return_(js.fun([],
	[js.return_(js(
	'this.$noSuchMethodName('
	'this, '
	'$createInvocationMirror('
	'name, short, type, '
	'$slice(arguments$sliceOffsetParam), []))'))]))]))
	])
	]);
	}
	}