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Google XML Pages (GXP) is a templating system used to generate XML/SGML markup (most often HTML).
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/*
* Copyright (C) 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.gxp.compiler.java;
import com.google.common.base.CharEscapers;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.gxp.compiler.alerts.AlertSink;
import com.google.gxp.compiler.alerts.common.MissingTypeError;
import com.google.gxp.compiler.base.JavaAnnotation;
import com.google.gxp.compiler.base.NativeType;
import com.google.gxp.compiler.base.OutputLanguage;
import com.google.gxp.compiler.codegen.OutputLanguageUtil;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Contains static functions for validating java expressions and types,
* and a couple additional java utility functions.
*/
public class JavaUtil extends OutputLanguageUtil {
private JavaUtil() {
super(RESERVED_WORDS, FORBIDDEN_OPS, OPS_FINDER,
CharEscapers.javaStringUnicodeEscaper(),
CharEscapers.javaStringEscaper());
}
// READ THIS BEFORE YOU CHANGE THE LIST BELOW!
//
// Urs asked that *all* Java operators be disabled. He said they can be
// re-enabled only if he or Amit P. is convinced. So the operators that
// are commented out of the lists below were explicitly allowed by one
// of them. If you want to enable other operators (by commenting them
// out of these lists) you need to talk to one of them.
private static final Set FORBIDDEN_OPS = ImmutableSet.of(
// simple boolean
// "!",
// "!=", again, we want to compute booleans
// "==",
// boolean connectives
// "&&", useful for stuff like "if x != null && x.condition()"
// "||", the alternative (nested if) requires repeating the else clause
// boolean comparators
// ">", useful for stuff like "only show this button if foo > bar"
// ">=",
// "<",
// "<=",
// arithmetic
// "*",
// "+",
// "-",
// "/",
// "%",
// unusual
// "?", needed for rowspan calculations
"instanceof",
// "new", Necessary for conversions, like EnumerationIterator
// bitwise
"^",
"~",
"&",
"<<",
">>",
">>>",
"|",
// assignment -- I can't imagine any reason why it would ever be a good
// idea to re-enable these,
"--",
"-=",
"/=",
"*=",
"&=",
"%=",
"++",
"+=",
"<<=",
"=",
">>=",
">>>=",
"|=",
"^=");
private static final String NOT_IN_CAST_LOOKAHEAD = "(?!\\s*[,)>])";
// the order is important! The '|' operator is non-greedy in
// regexes. Sorting in order of descending length works.
//
// Note that for the >>> and >> operators we use negative lookeahead to
// make sure that the item isn't followed by a comma, close paren or >.
// In this case we have a generic cast, not an operator. This is kind
// of a hack, and isn't 100% correct (it won't handle generic methods
// like someVar.>.someMethod() ) but I think it's the best
// we can do without much more sophisticated expression parsing
private static final Pattern OPS_FINDER = compileUnionPattern(
"\\binstanceof\\b",
Pattern.quote(">>>="),
Pattern.quote("<<="),
Pattern.quote(">>="),
Pattern.quote(">>>") + NOT_IN_CAST_LOOKAHEAD,
Pattern.quote("--"),
Pattern.quote("-="),
Pattern.quote("!="),
Pattern.quote("/="),
Pattern.quote("^="),
Pattern.quote("*="),
Pattern.quote("&&"),
Pattern.quote("&="),
Pattern.quote("%="),
Pattern.quote("++"),
Pattern.quote("+="),
Pattern.quote("<<"),
Pattern.quote("<="),
Pattern.quote("=="),
Pattern.quote(">="),
Pattern.quote(">>") + NOT_IN_CAST_LOOKAHEAD,
Pattern.quote("|="),
Pattern.quote("||"),
"\\bnew\\b",
Pattern.quote("-"),
Pattern.quote("!"),
Pattern.quote("/"),
Pattern.quote("^"),
Pattern.quote("~"),
Pattern.quote("*"),
Pattern.quote("&"),
Pattern.quote("%"),
Pattern.quote("+"),
Pattern.quote("<"),
Pattern.quote("="),
Pattern.quote(">"),
Pattern.quote("|"),
Pattern.quote("?")); // just use ? to find ternary operator...
private static final Set RESERVED_WORDS = ImmutableSet.of(
// keywords
"abstract",
"assert",
"boolean",
"break",
"byte",
"case",
"catch",
"char",
"class",
"const",
"continue",
"default",
"do",
"double",
"else",
"enum",
"extends",
"final",
"finally",
"float",
"for",
"goto",
"if",
"implements",
"import",
"instanceof",
"int",
"interface",
"long",
"native",
"new",
"package",
"private",
"protected",
"public",
"return",
"short",
"static",
"strictfp",
"super",
"switch",
"synchronized",
"this",
"throw",
"throws",
"transient",
"try",
"void",
"volatile",
"while",
// literals
"true",
"false",
"null");
private static final Set TYPE_ARGUMENT_QUALIFIERS
= ImmutableSet.of("extends", "super");
private static final Pattern IDENTIFIER_REGEX
= Pattern.compile("^[A-Za-z_][A-Za-z0-9_]*$");
private static final Pattern TYPE_TOKEN_REGEX
= Pattern.compile("^([A-Za-z_][A-Za-z0-9_]*|[\\?\\[\\]<>{},\\.])(.*)",
Pattern.DOTALL);
private static final Map PRIMITIVE_TO_BOXED_MAP =
ImmutableMap.builder()
.put("boolean", "Boolean")
.put("byte", "Number")
.put("char", "Character")
.put("double", "Number")
.put("float", "Number")
.put("int", "Number")
.put("long", "Number")
.put("short", "Number")
.build();
private static final Set PRIMITIVE_TYPES =
ImmutableSet.copyOf(PRIMITIVE_TO_BOXED_MAP.keySet());
public static final boolean isPrimitiveType(String s) {
return PRIMITIVE_TYPES.contains(s);
}
private static boolean isIdentifier(String s) {
return s != null
&& !RESERVED_WORDS.contains(s)
&& IDENTIFIER_REGEX.matcher(s).matches();
}
/**
* Validate the given NativeType and adds alerts to the sink if
* necessary.
*
* @return a String representing the validated type
*/
public static String validateType(AlertSink alertSink, NativeType type) {
String ret = type.getNativeType(OutputLanguage.JAVA);
if (ret == null) {
alertSink.add(new MissingTypeError(type, OutputLanguage.JAVA));
return ret;
}
ret = ret.replace('{', '<').replace('}', '>').trim();
// tokenize the type
Queue tokens = new LinkedList();
String s = type.getNativeType(OutputLanguage.JAVA).trim();
while (s.length() != 0) {
Matcher m = TYPE_TOKEN_REGEX.matcher(s);
if (m.find()) {
tokens.add(m.group(1));
s = m.group(2).trim();
} else {
alertSink.add(new IllegalJavaTypeError(type));
return ret;
}
}
if (!(parseType(tokens) && tokens.isEmpty())) {
alertSink.add(new IllegalJavaTypeError(type));
}
return ret;
}
/**
* Validate the given NativeType and adds alerts to the sink if
* necessary. Allows for conjunctive types (ex: Foo & Bar).
*
* This is taking a bit of a shortcut, as if java ever allowed something like
* "extends List & Baz" an alert would be incorrectly
* be generated. Java doesn't currently allow this though so we're fine.
*
* @return a String representing the validated type
*/
public static String validateConjunctiveType(AlertSink alertSink, NativeType type) {
List subTypes = Lists.newArrayList();
for (String subType : type.getNativeType(OutputLanguage.JAVA).split("&")) {
subTypes.add(validateType(alertSink, new NativeType(type, subType)));
}
return Joiner.on(" & ").join(subTypes);
}
/**
* Validate that the given {@link JavaAnnotation} contains a well formed
* Java annotation.
*
* @return the well formed annotation.
*/
public static String validateAnnotation(AlertSink alertSink, JavaAnnotation annotation) {
// TODO(harryh): actually do some validation
return annotation.getWith();
}
// Comments on parse functions are from the grammar in the Java 1.5
// Language Spec. Types in Java 1.5 are a bit complicated due to
// generics. They aren't regular (ie: cannot be matched by a regular
// expression), so we use a simple LL(1) recursive descent parser.
/**
* Parses the following rule from the JLS:
* Type:
* Identifier [TypeArguments]{ . Identifier [TypeArguments]} {[]}
* BasicType {[]}
* (actually, this rule deviates from the JLS, which seems to have a
* bug in that it doesn't allow arrays of BasicTypes)
*
* MODIFIED so that {}s can sub for <>s
*/
private static boolean parseType(Queue tokens) {
if (isPrimitiveType(tokens.peek())) {
tokens.poll();
} else {
while (true) {
if (!isIdentifier(tokens.poll())) {
return false;
}
if ("<".equals(tokens.peek())) {
if (!parseTypeArguments(tokens, "<", ">")) {
return false;
}
}
if ("{".equals(tokens.peek())) {
if (!parseTypeArguments(tokens, "{", "}")) {
return false;
}
}
if (".".equals(tokens.peek())) {
tokens.poll();
} else {
break;
}
}
}
while ("[".equals(tokens.peek())) {
tokens.poll();
if (!"]".equals(tokens.poll())) {
return false;
}
}
return true;
}
/**
* Parses the following rule from the JLS:
* TypeArguments:
* < TypeArgument {, TypeArgument} >
*
* MODIFIED so that {}s can sub for <>s
*/
private static boolean parseTypeArguments(Queue tokens,
String start, String end) {
if (!tokens.poll().equals(start)) {
return false;
}
while (true) {
if (!parseTypeArgument(tokens)) {
return false;
}
if (",".equals(tokens.peek())) {
tokens.poll();
} else {
break;
}
}
return (end.equals(tokens.poll()));
}
/**
* Parses the following rule from the JLS:
* TypeArgument:
* Type
* ? [( extends | super ) Type]
*/
private static boolean parseTypeArgument(Queue tokens) {
if ("?".equals(tokens.peek())) {
tokens.poll();
if (TYPE_ARGUMENT_QUALIFIERS.contains(tokens.peek())) {
tokens.poll();
return parseType(tokens);
}
} else {
return parseType(tokens);
}
return true;
}
//////////////////////////////////////////////////////////////////////
// Functions for moving back and forth between reference and
// primitive types
//////////////////////////////////////////////////////////////////////
/**
* @return the most general reference type that corresponds to the specified
* a Java type, or the specified Java type if it is already a reference type
* (ie: a class/interface).
*/
public static String toReferenceType(String type) {
String result = PRIMITIVE_TO_BOXED_MAP.get(type);
return (result == null) ? type : result;
}
public static String unbox(String expr, String type) {
if (PRIMITIVE_TO_BOXED_MAP.containsKey(type)) {
return "(" + expr + ")." + type + "Value()";
} else {
return expr;
}
}
//////////////////////////////////////////////////////////////////////
// Primitive Parsing
//////////////////////////////////////////////////////////////////////
// strcitly check for either "true" or "false"
private static final Predicate ISVALID_BOOLEAN
= new Predicate() {
public boolean apply(String s) {
s = s.trim();
return (s.equals("true") || s.equals("false"));
}
};
private static final Predicate ISVALID_BYTE
= new Predicate() {
public boolean apply(String s) {
Byte.valueOf(s.trim());
return true;
}
};
// as long as s is a single character return it unmodified
private static final Predicate ISVALID_CHAR
= new Predicate() {
public boolean apply(String s) {
return (s.length() == 1);
}
};
private static final Predicate ISVALID_DOUBLE
= new Predicate() {
public boolean apply(String s) {
Double.valueOf(s.trim());
return true;
}
};
private static final Predicate ISVALID_FLOAT
= new Predicate() {
public boolean apply(String s) {
Float.valueOf(s.trim());
return true;
}
};
private static final Predicate ISVALID_INT
= new Predicate() {
public boolean apply(String s) {
Integer.valueOf(s.trim());
return true;
}
};
private static final Predicate ISVALID_LONG
= new Predicate() {
public boolean apply(String s) {
Long.valueOf(s.trim());
return true;
}
};
private static final Predicate ISVALID_SHORT
= new Predicate() {
public boolean apply(String s) {
Short.valueOf(s.trim());
return true;
}
};
private static final Map> PRIMITIVE_TO_VALIDATOR
= ImmutableMap.>builder()
.put("boolean", ISVALID_BOOLEAN)
.put("byte", ISVALID_BYTE)
.put("char", ISVALID_CHAR)
.put("double", ISVALID_DOUBLE)
.put("float", ISVALID_FLOAT)
.put("int", ISVALID_INT)
.put("long", ISVALID_LONG)
.put("short", ISVALID_SHORT)
.build();
/**
* @return true if the primitive is a valid literal of the specified
* type, false otherwise.
*/
public static final boolean isValidPrimitive(String primitive, String type) {
try {
return PRIMITIVE_TO_VALIDATOR.get(type).apply(primitive);
} catch (NumberFormatException e) {
return false;
}
}
/**
* Static Singleton Instance
*
* Must be declared last in the source file.
*/
public static final JavaUtil INSTANCE = new JavaUtil();
}