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Documented the ClassFileMetaData utility.

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Reinier Zwitserloot committed 2010-08-15 23:19:15 +02:00
1 parent 240473a6c2
commit 431543afcd
2 files changed
+78 -19
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src/core/lombok/bytecode/ClassFileMetaData.java
+78 -5
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@@ -25,8 +25,10 @@ import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Utility to read the constant pool, header, and inheritance information of any class file.
*/
public class ClassFileMetaData {
private static final byte UTF8 = 1;
private static final byte INTEGER = 3;
private static final byte FLOAT = 4;
@@ -119,14 +121,31 @@ public class ClassFileMetaData {
return result.toString();
}
/**
* Checks if the constant pool contains the provided 'raw' string. These are used as source material for further JVM types, such as string constants, type references, etcetera.
*/
public boolean containsUtf8(String value) {
return findUtf8(value) != NOT_FOUND;
}
/**
* Checks if the constant pool contains a reference to the provided class.
*
* NB: Most uses of a type do <em>NOT</em> show up as a class in the constant pool.
* For example, the parameter types and return type of any method you invoke or declare, are stored as signatures and not as type references,
* but the type to which any method you invoke belongs, is. Read the JVM Specification for more information.
*
* @param className must be provided JVM-style, such as {@code java/lang/String}
*/
public boolean usesClass(String className) {
return findClass(className) != NOT_FOUND;
}
/**
* Checks if the constant pool contains a reference to a given field, either for writing or reading.
*
* @param className must be provided JVM-style, such as {@code java/lang/String}
*/
public boolean usesField(String className, String fieldName) {
int classIndex = findClass(className);
if (classIndex == NOT_FOUND) return false;
@@ -142,6 +161,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains a reference to a given method, with any signature (return type and parameter types).
*
* @param className must be provided JVM-style, such as {@code java/lang/String}
*/
public boolean usesMethod(String className, String methodName) {
int classIndex = findClass(className);
if (classIndex == NOT_FOUND) return false;
@@ -157,6 +181,12 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains a reference to a given method.
*
* @param className must be provided JVM-style, such as {@code java/lang/String}
* @param descriptor must be provided JVM-style, such as {@code (IZ)Ljava/lang/String;}
*/
public boolean usesMethod(String className, String methodName, String descriptor) {
int classIndex = findClass(className);
if (classIndex == NOT_FOUND) return false;
@@ -171,6 +201,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains the provided string constant, which implies the constant is used somewhere in the code.
*
* NB: String literals get concatenated by the compiler.
*/
public boolean containsStringConstant(String value) {
int index = findUtf8(value);
if (index == NOT_FOUND) return false;
@@ -180,6 +215,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains the provided long constant, which implies the constant is used somewhere in the code.
*
* NB: compile-time constant expressions are evaluated at compile time.
*/
public boolean containsLong(long value) {
for (int i = 1; i < maxPoolSize; i++) {
if (types[i] == LONG && readLong(i) == value) return true;
@@ -187,6 +227,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains the provided double constant, which implies the constant is used somewhere in the code.
*
* NB: compile-time constant expressions are evaluated at compile time.
*/
public boolean containsDouble(double value) {
boolean isNan = Double.isNaN(value);
for (int i = 1; i < maxPoolSize; i++) {
@@ -198,6 +243,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains the provided int constant, which implies the constant is used somewhere in the code.
*
* NB: compile-time constant expressions are evaluated at compile time.
*/
public boolean containsInteger(int value) {
for (int i = 1; i < maxPoolSize; i++) {
if (types[i] == INTEGER && readInteger(i) == value) return true;
@@ -205,6 +255,11 @@ public class ClassFileMetaData {
return false;
}
/**
* Checks if the constant pool contains the provided float constant, which implies the constant is used somewhere in the code.
*
* NB: compile-time constant expressions are evaluated at compile time.
*/
public boolean containsFloat(float value) {
boolean isNan = Float.isNaN(value);
for (int i = 1; i < maxPoolSize; i++) {
@@ -230,7 +285,7 @@ public class ClassFileMetaData {
private long readInteger(int index) {
return read32(offsets[index]);
}
private float readFloat(int index) {
return Float.intBitsToFloat(read32(offsets[index]));
}
@@ -238,15 +293,27 @@ public class ClassFileMetaData {
private int read32(int pos) {
return (byteCode[pos] & 0xFF) << 24 | (byteCode[pos + 1] & 0xFF) << 16 | (byteCode[pos + 2] & 0xFF) << 8 | (byteCode[pos + 3] &0xFF);
}
/**
* Returns the name of the class in JVM format, such as {@code java/lang/String}
*/
public String getClassName() {
return getClassName(readValue(endOfPool + 2));
}
/**
* Returns the name of the superclass in JVM format, such as {@code java/lang/Object}
*
* NB: If you try this on Object itself, you'll get {@code null}.<br />
* NB2: For interfaces and annotation interfaces, you'll always get {@code java/lang/Object}
*/
public String getSuperClassName() {
return getClassName(readValue(endOfPool + 4));
}
/**
* Returns the name of all implemented interfaces.
*/
public List<String> getInterfaces() {
int size = readValue(endOfPool + 6);
if (size == 0) return Collections.emptyList();
@@ -258,10 +325,16 @@ public class ClassFileMetaData {
return result;
}
/**
* A {@code toString()} like utility to dump all contents of the constant pool into a string.
*
* NB: No guarantees are made about the exact layout of this string. It is for informational purposes only, don't try to parse it.<br />
* NB2: After a double or long, there's a JVM spec-mandated gap, which is listed as {@code (cont.)} in the returned string.
*/
public String poolContent() {
StringBuilder result = new StringBuilder();
for (int i = 1; i < maxPoolSize; i++) {
result.append(String.format("#%02d: ", i));
result.append(String.format("#%02x: ", i));
int pos = offsets[i];
switch(types[i]) {
case UTF8:
@@ -359,4 +432,4 @@ public class ClassFileMetaData {
private int readValue(int position) {
return ((byteCode[position] & 0xFF) << 8) | (byteCode[position + 1] & 0xFF);
}
}
}
test/bytecode/src/lombok/bytecode/TestClassFileMetaData.java
-14
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@@ -49,20 +49,6 @@ public class TestClassFileMetaData {
private static ClassFileMetaData baz = create(new File("test/bytecode/resource/Baz.java"));
private static ClassFileMetaData buux = create(new File("test/bytecode/resource/Buux.java"));
// @Test
// public void dump() {
// byte[] bytes = compile(new File("test/bytecode/resource/Foo.java"));
// int count = 0;
// for (byte b : bytes) {
// System.out.printf("%02x ", (b & 0xFF));
// count++;
// if (count % 20 == 0) System.out.println();
// }
// System.out.println();
// System.out.println();
// System.out.println(foo.poolContent());
// }
@Test
public void testGetClassName() {
assertTrue(foo.containsUtf8("Foo"));