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Java example source code file (CompilerConstants.java)

This example Java source code file (CompilerConstants.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

call, class, compilerconstants, eval, fieldaccess, lazy, methodemitter, methodhandle, override, split_prefix, strict_mode, string, temp_prefix, this_debugger, util

The CompilerConstants.java Java example source code

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * 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
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.codegen;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.util.Iterator;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.Source;

/**
 * This class represents constant names of variables, methods and fields in
 * the compiler
 */

public enum CompilerConstants {
    /** the __FILE__ variable */
    __FILE__,

    /** the __DIR__ variable */
    __DIR__,

    /** the __LINE__ variable */
    __LINE__,

    /** lazy prefix for classes of jitted methods */
    LAZY("Lazy"),

    /** constructor name */
    INIT("<init>"),

    /** static initializer name */
    CLINIT("<clinit>"),

    /** eval name */
    EVAL("eval"),

    /** source name and class */
    SOURCE("source", Source.class),

    /** constants name and class */
    CONSTANTS("constants", Object[].class),

    /** strict mode field name and type */
    STRICT_MODE("strictMode", boolean.class),

    /** default script name */
    DEFAULT_SCRIPT_NAME("Script"),

    /** function prefix for anonymous functions */
    FUNCTION_PREFIX("function$"),

    /** method name for Java method that is script entry point */
    RUN_SCRIPT("runScript"),

    /**
     * "this" name symbol for a parameter representing ECMAScript "this" in static methods that are compiled
     * representations of ECMAScript functions. It is not assigned a slot, as its position in the method signature is
     * dependent on other factors (most notably, callee can precede it).
     */
    THIS("this"),

    /** this debugger symbol */
    THIS_DEBUGGER(":this"),

    /** scope name, type and slot */
    SCOPE(":scope", ScriptObject.class, 2),

    /** the return value variable name were intermediate results are stored for scripts */
    RETURN(":return"),

    /** the callee value variable when necessary */
    CALLEE(":callee", ScriptFunction.class),

    /** the varargs variable when necessary */
    VARARGS(":varargs", Object[].class),

    /** the arguments variable (visible to function body). Initially set to ARGUMENTS, but can be reassigned by code in
     * the function body.*/
    ARGUMENTS_VAR("arguments", Object.class),

    /** the internal arguments object, when necessary (not visible to scripts, can't be reassigned). */
    ARGUMENTS(":arguments", ScriptObject.class),

    /** prefix for iterators for for (x in ...) */
    ITERATOR_PREFIX(":i", Iterator.class),

    /** prefix for tag variable used for switch evaluation */
    SWITCH_TAG_PREFIX(":s"),

    /** prefix for all exceptions */
    EXCEPTION_PREFIX(":e", Throwable.class),

    /** prefix for quick slots generated in Store */
    QUICK_PREFIX(":q"),

    /** prefix for temporary variables */
    TEMP_PREFIX(":t"),

    /** prefix for literals */
    LITERAL_PREFIX(":l"),

    /** prefix for regexps */
    REGEX_PREFIX(":r"),

    /** "this" used in non-static Java methods; always in slot 0 */
    JAVA_THIS(null, 0),

    /** Map parameter in scope object constructors; always in slot 1 */
    INIT_MAP(null, 1),

    /** Parent scope parameter in scope object constructors; always in slot 2 */
    INIT_SCOPE(null, 2),

    /** Arguments parameter in scope object constructors; in slot 3 when present */
    INIT_ARGUMENTS(null, 3),

    /** prefix for all ScriptObject subclasses with fields, @see ObjectGenerator */
    JS_OBJECT_PREFIX("JO"),

    /** name for allocate method in JO objects */
    ALLOCATE("allocate"),

    /** prefix for split methods, @see Splitter */
    SPLIT_PREFIX("$split"),

    /** prefix for split array method and slot */
    SPLIT_ARRAY_ARG("split_array", 3),

    /** get string from constant pool */
    GET_STRING("$getString"),

    /** get map */
    GET_MAP("$getMap"),

    /** get map */
    SET_MAP("$setMap"),

    /** get array prefix */
    GET_ARRAY_PREFIX("$get"),

    /** get array suffix */
    GET_ARRAY_SUFFIX("$array");

    private final String symbolName;
    private final Class<?> type;
    private final int slot;

    private CompilerConstants() {
        this.symbolName = name();
        this.type = null;
        this.slot = -1;
    }

    private CompilerConstants(final String symbolName) {
        this(symbolName, -1);
    }

    private CompilerConstants(final String symbolName, final int slot) {
        this(symbolName, null, slot);
    }

    private CompilerConstants(final String symbolName, final Class<?> type) {
        this(symbolName, type, -1);
    }

    private CompilerConstants(final String symbolName, final Class<?> type, final int slot) {
        this.symbolName  = symbolName;
        this.type = type;
        this.slot = slot;
    }

    /**
     * Return the tag for this compile constant. Deliberately avoiding "name" here
     * not to conflate with enum implementation. This is the master string for the
     * constant - every constant has one.
     *
     * @return the tag
     */
    public final String symbolName() {
        return symbolName;
    }

    /**
     * Return the type for this compile constant
     *
     * @return type for this constant's instances, or null if N/A
     */
    public final Class<?> type() {
        return type;
    }

    /**
     * Return the slot for this compile constant
     *
     * @return byte code slot where constant is stored or -1 if N/A
     */
    public final int slot() {
        return slot;
    }

    /**
     * Return a descriptor for this compile constant. Only relevant if it has
     * a type
     *
     * @return descriptor the descriptor
     */
    public final String descriptor() {
        assert type != null : " asking for descriptor of typeless constant";
        return typeDescriptor(type);
    }

    /**
     * Get the internal class name for a type
     *
     * @param type a type
     * @return  the internal name for this type
     */
    public static String className(final Class<?> type) {
        return Type.getInternalName(type);
    }

    /**
     * Get the method descriptor for a given method type collection
     *
     * @param rtype  return type
     * @param ptypes parameter types
     *
     * @return internal descriptor for this method
     */
    public static String methodDescriptor(final Class<?> rtype, final Class... ptypes) {
        return Type.getMethodDescriptor(rtype, ptypes);
    }

    /**
     * Get the type descriptor for a type
     *
     * @param clazz a type
     *
     * @return the internal descriptor for this type
     */
    public static String typeDescriptor(final Class<?> clazz) {
        return Type.typeFor(clazz).getDescriptor();
    }

    /**
     * Create a call representing a void constructor for a given type. Don't
     * attempt to look this up at compile time
     *
     * @param clazz the class
     *
     * @return Call representing void constructor for type
     */
    public static Call constructorNoLookup(final Class<?> clazz) {
        return specialCallNoLookup(clazz, INIT.symbolName(), void.class);
    }

    /**
     * Create a call representing a constructor for a given type. Don't
     * attempt to look this up at compile time
     *
     * @param className the type class name
     * @param ptypes    the parameter types for the constructor
     *
     * @return Call representing constructor for type
     */
    public static Call constructorNoLookup(final String className, final Class<?>... ptypes) {
        return specialCallNoLookup(className, INIT.symbolName(), methodDescriptor(void.class, ptypes));
    }

    /**
     * Create a call representing a constructor for a given type. Don't
     * attempt to look this up at compile time
     *
     * @param clazz  the class name
     * @param ptypes the parameter types for the constructor
     *
     * @return Call representing constructor for type
     */
    public static Call constructorNoLookup(final Class<?> clazz, final Class... ptypes) {
        return specialCallNoLookup(clazz, INIT.symbolName(), void.class, ptypes);
    }

    /**
     * Create a call representing an invokespecial to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param className the class name
     * @param name      the method name
     * @param desc      the descriptor
     *
     * @return Call representing specified invokespecial call
     */
    public static Call specialCallNoLookup(final String className, final String name, final String desc) {
        return new Call(null, className, name, desc) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokespecial(className, name, descriptor);
            }
        };
    }

    /**
     * Create a call representing an invokespecial to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param clazz  the class
     * @param name   the method name
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return Call representing specified invokespecial call
     */
    public static Call specialCallNoLookup(final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return specialCallNoLookup(className(clazz), name, methodDescriptor(rtype, ptypes));
    }

    /**
     * Create a call representing an invokestatic to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param className the class name
     * @param name      the method name
     * @param desc      the descriptor
     *
     * @return Call representing specified invokestatic call
     */
    public static Call staticCallNoLookup(final String className, final String name, final String desc) {
        return new Call(null, className, name, desc) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokestatic(className, name, descriptor);
            }
        };
    }

    /**
     * Create a call representing an invokestatic to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param clazz  the class
     * @param name   the method name
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return Call representing specified invokestatic call
     */
    public static Call staticCallNoLookup(final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return staticCallNoLookup(className(clazz), name, methodDescriptor(rtype, ptypes));
    }

    /**
     * Create a call representing an invokevirtual to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param clazz  the class
     * @param name   the method name
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return Call representing specified invokevirtual call
     */
    public static Call virtualCallNoLookup(final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return new Call(null, className(clazz), name, methodDescriptor(rtype, ptypes)) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokevirtual(className, name, descriptor);
            }
        };
    }

    /**
     * Create a call representing an invokeinterface to a given method. Don't
     * attempt to look this up at compile time
     *
     * @param clazz  the class
     * @param name   the method name
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return Call representing specified invokeinterface call
     */
    public static Call interfaceCallNoLookup(final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return new Call(null, className(clazz), name, methodDescriptor(rtype, ptypes)) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokeinterface(className, name, descriptor);
            }
        };
    }

    /**
     * Create a FieldAccess representing a virtual field, that can be subject to put
     * or get operations
     *
     * @param className name of the class where the field is a member
     * @param name      name of the field
     * @param desc      type descriptor of the field
     *
     * @return a field access object giving access code generation method for the virtual field
     */
    public static FieldAccess virtualField(final String className, final String name, final String desc) {
        return new FieldAccess(className, name, desc) {
            @Override
            public MethodEmitter get(final MethodEmitter method) {
                return method.getField(className, name, descriptor);
            }

            @Override
            public void put(final MethodEmitter method) {
                method.putField(className, name, descriptor);
            }
        };
    }

    /**
     * Create a FieldAccess representing a virtual field, that can be subject to put
     * or get operations
     *
     * @param clazz class where the field is a member
     * @param name  name of the field
     * @param type  type of the field
     *
     * @return a field access object giving access code generation method for the virtual field
     */
    public static FieldAccess virtualField(final Class<?> clazz, final String name, final Class type) {
        return virtualField(className(clazz), name, typeDescriptor(type));
    }

    /**
     * Create a FieldAccess representing a static field, that can be subject to put
     * or get operations
     *
     * @param className name of the class where the field is a member
     * @param name      name of the field
     * @param desc      type descriptor of the field
     *
     * @return a field access object giving access code generation method for the static field
     */
    public static FieldAccess staticField(final String className, final String name, final String desc) {
        return new FieldAccess(className, name, desc) {
            @Override
            public MethodEmitter get(final MethodEmitter method) {
                return method.getStatic(className, name, descriptor);
            }

            @Override
            public void put(final MethodEmitter method) {
                method.putStatic(className, name, descriptor);
            }
        };
    }

    /**
     * Create a FieldAccess representing a static field, that can be subject to put
     * or get operations
     *
     * @param clazz class where the field is a member
     * @param name  name of the field
     * @param type  type of the field
     *
     * @return a field access object giving access code generation method for the virtual field
     */
    public static FieldAccess staticField(final Class<?> clazz, final String name, final Class type) {
        return staticField(className(clazz), name, typeDescriptor(type));
    }

    /**
     * Create a static call, given an explicit lookup, looking up the method handle for it at the same time
     *
     * @param lookup the lookup
     * @param clazz  the class
     * @param name   the name of the method
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return the call object representing the static call
     */
    public static Call staticCall(final MethodHandles.Lookup lookup, final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return new Call(MH.findStatic(lookup, clazz, name, MH.type(rtype, ptypes)), className(clazz), name, methodDescriptor(rtype, ptypes)) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokestatic(className, name, descriptor);
            }
        };
    }

    /**
     * Create a virtual call, given an explicit lookup, looking up the method handle for it at the same time
     *
     * @param lookup the lookup
     * @param clazz  the class
     * @param name   the name of the method
     * @param rtype  the return type
     * @param ptypes the parameter types
     *
     * @return the call object representing the virtual call
     */
    public static Call virtualCall(final MethodHandles.Lookup lookup, final Class<?> clazz, final String name, final Class rtype, final Class... ptypes) {
        return new Call(MH.findVirtual(lookup, clazz, name, MH.type(rtype, ptypes)), className(clazz), name, methodDescriptor(rtype, ptypes)) {
            @Override
            public MethodEmitter invoke(final MethodEmitter method) {
                return method.invokevirtual(className, name, descriptor);
            }
        };
    }

    /**
     * Private class representing an access. This can generate code into a method code or
     * a field access.
     */
    private abstract static class Access {
        protected final MethodHandle methodHandle;
        protected final String       className;
        protected final String       name;
        protected final String       descriptor;

        /**
         * Constructor
         *
         * @param methodHandle methodHandle or null if none
         * @param className    class name for access
         * @param name         field or method name for access
         * @param descriptor   descriptor for access field or method
         */
        protected Access(final MethodHandle methodHandle, final String className, final String name, final String descriptor) {
            this.methodHandle = methodHandle;
            this.className    = className;
            this.name         = name;
            this.descriptor   = descriptor;
        }

        /**
         * Get the method handle, or null if access hasn't been looked up
         *
         * @return method handle
         */
        public MethodHandle methodHandle() {
            return methodHandle;
        }

        /**
         * Get the class name of the access
         *
         * @return the class name
         */
        public String className() {
            return className;
        }

        /**
         * Get the field name or method name of the access
         *
         * @return the name
         */
        public String name() {
            return name;
        }

        /**
         * Get the descriptor of the method or field of the access
         *
         * @return the descriptor
         */
        public String descriptor() {
            return descriptor;
        }
    }

    /**
     * Field access - this can be used for generating code for static or
     * virtual field accesses
     */
    public abstract static class FieldAccess extends Access {
        /**
         * Constructor
         *
         * @param className  name of the class where the field is
         * @param name       name of the field
         * @param descriptor descriptor of the field
         */
        protected FieldAccess(final String className, final String name, final String descriptor) {
            super(null, className, name, descriptor);
        }

        /**
         * Generate get code for the field
         *
         * @param emitter a method emitter
         *
         * @return the method emitter
         */
        protected abstract MethodEmitter get(final MethodEmitter emitter);

        /**
         * Generate put code for the field
         *
         * @param emitter a method emitter
         */
        protected abstract void put(final MethodEmitter emitter);
    }

    /**
     * Call - this can be used for generating code for different types of calls
     */
    public abstract static class Call extends Access {

        /**
         * Constructor
         *
         * @param className  class name for the method of the call
         * @param name       method name
         * @param descriptor method descriptor
         */
        protected Call(final String className, final String name, final String descriptor) {
            super(null, className, name, descriptor);
        }

        /**
         * Constructor
         *
         * @param methodHandle method handle for the call if resolved
         * @param className    class name for the method of the call
         * @param name         method name
         * @param descriptor   method descriptor
         */
        protected Call(final MethodHandle methodHandle, final String className, final String name, final String descriptor) {
            super(methodHandle, className, name, descriptor);
        }

        /**
         * Generate invocation code for the method
         *
         * @param emitter a method emitter
         *
         * @return the method emitter
         */
        protected abstract MethodEmitter invoke(final MethodEmitter emitter);
    }

}

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