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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package sun.reflect.generics.parser;
import java.lang.reflect.GenericSignatureFormatError;
import java.util.*;
import sun.reflect.generics.tree.*;
/**
* Parser for type signatures, as defined in the Java Virtual
// Machine Specification (JVMS) chapter 4.
* Converts the signatures into an abstract syntax tree (AST) representation.
// See the package sun.reflect.generics.tree for details of the AST.
*/
public class SignatureParser {
// The input is conceptually a character stream (though currently it's
// a string). This is slightly different than traditional parsers,
// because there is no lexical scanner performing tokenization.
// Having a separate tokenizer does not fit with the nature of the
// input format.
// Other than the absence of a tokenizer, this parser is a classic
// recursive descent parser. Its structure corresponds as closely
// as possible to the grammar in the JVMS.
//
// A note on asserts vs. errors: The code contains assertions
// in situations that should never occur. An assertion failure
// indicates a failure of the parser logic. A common pattern
// is an assertion that the current input is a particular
// character. This is often paired with a separate check
// that this is the case, which seems redundant. For example:
//
// assert(current() != x);
// if (current != x {error("expected an x");
//
// where x is some character constant.
// The assertion inidcates, that, as currently written,
// the code should nver reach this point unless the input is an
// x. On the other hand, the test is there to check the legality
// of the input wrt to a given production. It may be that at a later
// time the code might be called directly, and if the input is
// invalid, the parser should flag an error in accordance
// with its logic.
private char[] input; // the input signature
private int index = 0; // index into the input
// used to mark end of input
private static final char EOI = ':';
private static final boolean DEBUG = false;
// private constructor - enforces use of static factory
private SignatureParser(){}
// Utility methods.
// Most parsing routines use the following routines to access the
// input stream, and advance it as necessary.
// This makes it easy to adapt the parser to operate on streams
// of various kinds as well as strings.
// returns current element of the input and advances the input
private char getNext(){
assert(index <= input.length);
try {
return input[index++];
} catch (ArrayIndexOutOfBoundsException e) { return EOI;}
}
// returns current element of the input
private char current(){
assert(index <= input.length);
try {
return input[index];
} catch (ArrayIndexOutOfBoundsException e) { return EOI;}
}
// advance the input
private void advance(){
assert(index <= input.length);
index++;
}
// Match c against a "set" of characters
private boolean matches(char c, char... set) {
for (char e : set) {
if (c == e) return true;
}
return false;
}
// Error handling routine. Encapsulates error handling.
// Takes a string error message as argument.
// Currently throws a GenericSignatureFormatError.
private Error error(String errorMsg) {
if (DEBUG) System.out.println("Parse error:" + errorMsg);
return new GenericSignatureFormatError();
}
/**
* Static factory method. Produces a parser instance.
* @return an instance of <tt>SignatureParser</tt>
*/
public static SignatureParser make() {
return new SignatureParser();
}
/**
* Parses a class signature (as defined in the JVMS, chapter 4)
* and produces an abstract syntax tree representing it.
* @param s a string representing the input class signature
* @return An abstract syntax tree for a class signature
* corresponding to the input string
* @throws GenericSignatureFormatError if the input is not a valid
* class signature
*/
public ClassSignature parseClassSig(String s) {
if (DEBUG) System.out.println("Parsing class sig:" + s);
input = s.toCharArray();
return parseClassSignature();
}
/**
* Parses a method signature (as defined in the JVMS, chapter 4)
* and produces an abstract syntax tree representing it.
* @param s a string representing the input method signature
* @return An abstract syntax tree for a method signature
* corresponding to the input string
* @throws GenericSignatureFormatError if the input is not a valid
* method signature
*/
public MethodTypeSignature parseMethodSig(String s) {
if (DEBUG) System.out.println("Parsing method sig:" + s);
input = s.toCharArray();
return parseMethodTypeSignature();
}
/**
* Parses a type signature
* and produces an abstract syntax tree representing it.
* @param s a string representing the input type signature
* @return An abstract syntax tree for a type signature
* corresponding to the input string
* @throws GenericSignatureFormatError if the input is not a valid
* type signature
*/
public TypeSignature parseTypeSig(String s) {
if (DEBUG) System.out.println("Parsing type sig:" + s);
input = s.toCharArray();
return parseTypeSignature();
}
// Parsing routines.
// As a rule, the parsing routines access the input using the
// utilities current(), getNext() and/or advance().
// The convention is that when a parsing routine is invoked
// it expects the current input to be the first character it should parse
// and when it completes parsing, it leaves the input at the first
// character after the input parses.
// parse a class signature based on the implicit input.
private ClassSignature parseClassSignature() {
assert(index == 0);
return ClassSignature.make(parseZeroOrMoreFormalTypeParameters(),
parseClassTypeSignature(),
parseSuperInterfaces());
}
private FormalTypeParameter[] parseZeroOrMoreFormalTypeParameters(){
if (current() == '<') { return parseFormalTypeParameters();}
else {return new FormalTypeParameter[0];}
}
private FormalTypeParameter[] parseFormalTypeParameters(){
Collection<FormalTypeParameter> ftps =
new ArrayList<FormalTypeParameter>(3);
assert(current() == '<'); // should not have been called at all
if (current() != '<') { throw error("expected <");}
advance();
ftps.add(parseFormalTypeParameter());
while (current() != '>') {
ftps.add(parseFormalTypeParameter());
}
advance();
FormalTypeParameter[] ftpa = new FormalTypeParameter[ftps.size()];
return ftps.toArray(ftpa);
}
private FormalTypeParameter parseFormalTypeParameter(){
String id = parseIdentifier();
FieldTypeSignature[] bs = parseZeroOrMoreBounds();
return FormalTypeParameter.make(id, bs);
}
private String parseIdentifier(){
StringBuilder result = new StringBuilder();
while (!Character.isWhitespace(current())) {
char c = current();
switch(c) {
case ';':
case '.':
case '/':
case '[':
case ':':
case '>':
case '<': return result.toString();
default:{
result.append(c);
advance();
}
}
}
return result.toString();
}
private FieldTypeSignature parseFieldTypeSignature() {
switch(current()) {
case 'L':
return parseClassTypeSignature();
case 'T':
return parseTypeVariableSignature();
case '[':
return parseArrayTypeSignature();
default: throw error("Expected Field Type Signature");
}
}
private ClassTypeSignature parseClassTypeSignature(){
assert(current() == 'L');
if (current() != 'L') { throw error("expected a class type");}
advance();
List<SimpleClassTypeSignature> scts =
new ArrayList<SimpleClassTypeSignature>(5);
scts.add(parseSimpleClassTypeSignature(false));
parseClassTypeSignatureSuffix(scts);
if (current() != ';')
throw error("expected ';' got '" + current() + "'");
advance();
return ClassTypeSignature.make(scts);
}
private SimpleClassTypeSignature parseSimpleClassTypeSignature(boolean dollar){
String id = parseIdentifier();
char c = current();
switch (c) {
case ';':
case '/':
return SimpleClassTypeSignature.make(id, dollar, new TypeArgument[0]) ;
case '<': {
return SimpleClassTypeSignature.make(id, dollar, parseTypeArguments());
}
default: {throw error("expected < or ; or /");}
}
}
private void parseClassTypeSignatureSuffix(List<SimpleClassTypeSignature> scts) {
while (current() == '/' || current() == '.') {
boolean dollar = (current() == '.');
advance();
scts.add(parseSimpleClassTypeSignature(dollar));
}
}
private TypeArgument[] parseTypeArgumentsOpt() {
if (current() == '<') {return parseTypeArguments();}
else {return new TypeArgument[0];}
}
private TypeArgument[] parseTypeArguments() {
Collection<TypeArgument> tas = new ArrayList<TypeArgument>(3);
assert(current() == '<');
if (current() != '<') { throw error("expected <");}
advance();
tas.add(parseTypeArgument());
while (current() != '>') {
//(matches(current(), '+', '-', 'L', '[', 'T', '*')) {
tas.add(parseTypeArgument());
}
advance();
TypeArgument[] taa = new TypeArgument[tas.size()];
return tas.toArray(taa);
}
private TypeArgument parseTypeArgument() {
FieldTypeSignature[] ub, lb;
ub = new FieldTypeSignature[1];
lb = new FieldTypeSignature[1];
TypeArgument[] ta = new TypeArgument[0];
char c = current();
switch (c) {
case '+': {
advance();
ub[0] = parseFieldTypeSignature();
lb[0] = BottomSignature.make(); // bottom
return Wildcard.make(ub, lb);
}
case '*':{
advance();
ub[0] = SimpleClassTypeSignature.make("java.lang.Object", false, ta);
lb[0] = BottomSignature.make(); // bottom
return Wildcard.make(ub, lb);
}
case '-': {
advance();
lb[0] = parseFieldTypeSignature();
ub[0] = SimpleClassTypeSignature.make("java.lang.Object", false, ta);
return Wildcard.make(ub, lb);
}
default: return parseFieldTypeSignature();
}
}
// TypeVariableSignature -> T identifier
private TypeVariableSignature parseTypeVariableSignature(){
assert(current() == 'T');
if (current() != 'T') { throw error("expected a type variable usage");}
advance();
TypeVariableSignature ts =
TypeVariableSignature.make(parseIdentifier());
if (current() != ';') {
throw error("; expected in signature of type variable named" +
ts.getIdentifier());
}
advance();
return ts;
}
// ArrayTypeSignature -> [ TypeSignature
private ArrayTypeSignature parseArrayTypeSignature() {
if (current() != '[') {throw error("expected array type signature");}
advance();
return ArrayTypeSignature.make(parseTypeSignature());
}
// TypeSignature -> BaseType | FieldTypeSignature
private TypeSignature parseTypeSignature() {
switch (current()) {
case 'B':
case 'C':
case 'D':
case 'F':
case 'I':
case 'J':
case 'S':
case 'Z':return parseBaseType();
default: return parseFieldTypeSignature();
}
}
private BaseType parseBaseType() {
switch(current()) {
case 'B':
advance();
return ByteSignature.make();
case 'C':
advance();
return CharSignature.make();
case 'D':
advance();
return DoubleSignature.make();
case 'F':
advance();
return FloatSignature.make();
case 'I':
advance();
return IntSignature.make();
case 'J':
advance();
return LongSignature.make();
case 'S':
advance();
return ShortSignature.make();
case 'Z':
advance();
return BooleanSignature.make();
default: {
assert(false);
throw error("expected primitive type");
}
}
}
private FieldTypeSignature[] parseZeroOrMoreBounds() {
Collection<FieldTypeSignature> fts =
new ArrayList<FieldTypeSignature>(3);
if (current() == ':') {
advance();
switch(current()) {
case ':': // empty class bound
break;
default: // parse class bound
fts.add(parseFieldTypeSignature());
}
// zero or more interface bounds
while (current() == ':') {
advance();
fts.add(parseFieldTypeSignature());
}
}
FieldTypeSignature[] fta = new FieldTypeSignature[fts.size()];
return fts.toArray(fta);
}
private ClassTypeSignature[] parseSuperInterfaces() {
Collection<ClassTypeSignature> cts =
new ArrayList<ClassTypeSignature>(5);
while(current() == 'L') {
cts.add(parseClassTypeSignature());
}
ClassTypeSignature[] cta = new ClassTypeSignature[cts.size()];
return cts.toArray(cta);
}
// parse a method signature based on the implicit input.
private MethodTypeSignature parseMethodTypeSignature() {
FieldTypeSignature[] ets;
assert(index == 0);
return MethodTypeSignature.make(parseZeroOrMoreFormalTypeParameters(),
parseFormalParameters(),
parseReturnType(),
parseZeroOrMoreThrowsSignatures());
}
// (TypeSignature*)
private TypeSignature[] parseFormalParameters() {
if (current() != '(') {throw error("expected (");}
advance();
TypeSignature[] pts = parseZeroOrMoreTypeSignatures();
if (current() != ')') {throw error("expected )");}
advance();
return pts;
}
// TypeSignature*
private TypeSignature[] parseZeroOrMoreTypeSignatures() {
Collection<TypeSignature> ts = new ArrayList<TypeSignature>();
boolean stop = false;
while (!stop) {
switch(current()) {
case 'B':
case 'C':
case 'D':
case 'F':
case 'I':
case 'J':
case 'S':
case 'Z':
case 'L':
case 'T':
case '[': {
ts.add(parseTypeSignature());
break;
}
default: stop = true;
}
}
/* while( matches(current(),
'B', 'C', 'D', 'F', 'I', 'J', 'S', 'Z', 'L', 'T', '[')
) {
ts.add(parseTypeSignature());
}*/
TypeSignature[] ta = new TypeSignature[ts.size()];
return ts.toArray(ta);
}
// ReturnType -> V | TypeSignature
private ReturnType parseReturnType(){
if (current() == 'V') {
advance();
return VoidDescriptor.make();
} else return parseTypeSignature();
}
// ThrowSignature*
private FieldTypeSignature[] parseZeroOrMoreThrowsSignatures(){
Collection<FieldTypeSignature> ets =
new ArrayList<FieldTypeSignature>(3);
while( current() == '^') {
ets.add(parseThrowsSignature());
}
FieldTypeSignature[] eta = new FieldTypeSignature[ets.size()];
return ets.toArray(eta);
}
// ThrowSignature -> ^ FieldTypeSignature
private FieldTypeSignature parseThrowsSignature() {
assert(current() == '^');
if (current() != '^') { throw error("expected throws signature");}
advance();
return parseFieldTypeSignature();
}
}