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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package jdk.nashorn.internal.codegen;

import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.TreeSet;
import jdk.nashorn.internal.ir.CompileUnitHolder;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.runtime.RecompilableScriptFunctionData;

Used to track split class compilation. Note that instances of the class are serializable, but all fields are transient, making the serialized version of the class only useful for tracking the referential topology of other AST nodes referencing the same or different compile units. We do want to preserve this topology though as CompileUnitHolders in a deserialized AST will undergo reinitialization. /**
  * Used to track split class compilation. Note that instances of the class are serializable, but all fields are
  * transient, making the serialized version of the class only useful for tracking the referential topology of other
  * AST nodes referencing the same or different compile units. We do want to preserve this topology though as
  * {@link CompileUnitHolder}s in a deserialized AST will undergo reinitialization.
  */
public final class CompileUnit implements Comparable<CompileUnit>, Serializable {
    private static final long serialVersionUID = 1L;

    
Current class name /** Current class name */
    private transient final String className;

    
Current class generator /** Current class generator */
    private transient ClassEmitter classEmitter;

    private transient long weight;

    private transient Class<?> clazz;

    private final transient Map<FunctionNode, RecompilableScriptFunctionData> functions = new IdentityHashMap<>();

    private transient boolean isUsed;

    private static int emittedUnitCount;

    CompileUnit(final String className, final ClassEmitter classEmitter, final long initialWeight) {
        this.className    = className;
        this.weight       = initialWeight;
        this.classEmitter = classEmitter;
    }

    static Set<CompileUnit> createCompileUnitSet() {
        return new TreeSet<>();
    }

    static void increaseEmitCount() {
        emittedUnitCount++;
    }

    
Get the amount of emitted compile units so far in the system
Returns:
emitted compile unit count/**
     * Get the amount of emitted compile units so far in the system
     * @return emitted compile unit count
     */
    public static int getEmittedUnitCount() {
        return emittedUnitCount;
    }

    
Check if this compile unit is used
Returns:
true if tagged as in use - i.e active code that needs to be generated/**
     * Check if this compile unit is used
     * @return true if tagged as in use - i.e active code that needs to be generated
     */
    public boolean isUsed() {
        return isUsed;
    }

    
Check if a compile unit has code, not counting inits and clinits
Returns:
true of if there is "real code" in the compile unit/**
     * Check if a compile unit has code, not counting inits and clinits
     * @return true of if there is "real code" in the compile unit
     */
    public boolean hasCode() {
        return (classEmitter.getMethodCount() - classEmitter.getInitCount() - classEmitter.getClinitCount()) > 0;
    }

    
Tag this compile unit as used
/**
     * Tag this compile unit as used
     */
    public void setUsed() {
        this.isUsed = true;
    }

    
Return the class that contains the code for this unit, null if not
generated yet
Returns:
class with compile unit code/**
     * Return the class that contains the code for this unit, null if not
     * generated yet
     *
     * @return class with compile unit code
     */
    public Class<?> getCode() {
        return clazz;
    }

    
Set class when it exists. Only accessible from compiler
Params:
clazz – class with code for this compile unit/**
     * Set class when it exists. Only accessible from compiler
     * @param clazz class with code for this compile unit
     */
    void setCode(final Class<?> clazz) {
        this.clazz = Objects.requireNonNull(clazz);
        // Revisit this - refactor to avoid null-ed out non-final fields
        // null out emitter
        this.classEmitter = null;
    }

    void addFunctionInitializer(final RecompilableScriptFunctionData data, final FunctionNode functionNode) {
        functions.put(functionNode, data);
    }

    
Returns true if this compile unit is responsible for initializing the specified function data with specified
function node.
Params:
data – the function data to check
functionNode – the function node to check
Returns:
true if this unit is responsible for initializing the function data with the function node, otherwise
false/**
     * Returns true if this compile unit is responsible for initializing the specified function data with specified
     * function node.
     * @param data the function data to check
     * @param functionNode the function node to check
     * @return true if this unit is responsible for initializing the function data with the function node, otherwise
     * false
     */
    public boolean isInitializing(final RecompilableScriptFunctionData data, final FunctionNode functionNode) {
        return functions.get(functionNode) == data;
    }

    void initializeFunctionsCode() {
        for(final Map.Entry<FunctionNode, RecompilableScriptFunctionData> entry : functions.entrySet()) {
            entry.getValue().initializeCode(entry.getKey());
        }
    }

    Collection<FunctionNode> getFunctionNodes() {
        return Collections.unmodifiableCollection(functions.keySet());
    }

    
Add weight to this compile unit
Params:
w – weight to add/**
     * Add weight to this compile unit
     * @param w weight to add
     */
    void addWeight(final long w) {
        this.weight += w;
    }

    
Check if this compile unit can hold weight more units of weight 
Params:
w – weight to check if can be added
Returns:
true if weight fits in this compile unit/**
     * Check if this compile unit can hold {@code weight} more units of weight
     * @param w weight to check if can be added
     * @return true if weight fits in this compile unit
     */
    public boolean canHold(final long w) {
        return (this.weight + w) < Splitter.SPLIT_THRESHOLD;
    }

    
Get the class emitter for this compile unit
Returns:
class emitter/**
     * Get the class emitter for this compile unit
     * @return class emitter
     */
    public ClassEmitter getClassEmitter() {
        return classEmitter;
    }

    
Get the class name for this compile unit
Returns:
the class name/**
     * Get the class name for this compile unit
     * @return the class name
     */
    public String getUnitClassName() {
        return className;
    }

    private static String shortName(final String name) {
        return name == null ? null : name.lastIndexOf('/') == -1 ? name : name.substring(name.lastIndexOf('/') + 1);
    }

    @Override
    public String toString() {
        final String methods = classEmitter != null ? classEmitter.getMethodNames().toString() : "<anon>";
        return "[CompileUnit className=" + shortName(className) + " weight=" + weight + '/' + Splitter.SPLIT_THRESHOLD + " hasCode=" + methods + ']';
    }

    @Override
    public int compareTo(final CompileUnit o) {
        return className.compareTo(o.className);
    }
}