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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package jdk.nashorn.internal.ir;

import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import jdk.nashorn.internal.codegen.Label;
import jdk.nashorn.internal.ir.annotations.Immutable;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;

IR representation for a list of statements.
/**
 * IR representation for a list of statements.
 */
@Immutable
public class Block extends Node implements BreakableNode, Terminal, Flags<Block> {
    private static final long serialVersionUID = 1L;

    
List of statements /** List of statements */
    protected final List<Statement> statements;

    
Symbol table - keys must be returned in the order they were put in. /** Symbol table - keys must be returned in the order they were put in. */
    protected final Map<String, Symbol> symbols;

    
Entry label. /** Entry label. */
    private final Label entryLabel;

    
Break label. /** Break label. */
    private final Label breakLabel;

    
Does the block/function need a new scope? Is this synthetic? /** Does the block/function need a new scope? Is this synthetic? */
    protected final int flags;

    
See Also:
JoinPredecessor/**
     * @see JoinPredecessor
     */
    private final LocalVariableConversion conversion;

    
Flag indicating that this block needs scope /** Flag indicating that this block needs scope */
    public static final int NEEDS_SCOPE        = 1 << 0;

    
Is this block tagged as terminal based on its contents
(usually the last statement)
/**
     * Is this block tagged as terminal based on its contents
     * (usually the last statement)
     */
    public static final int IS_TERMINAL        = 1 << 2;

    
Is this block the eager global scope - i.e. the original program. This isn't true for the
outermost level of recompiles
/**
     * Is this block the eager global scope - i.e. the original program. This isn't true for the
     * outermost level of recompiles
     */
    public static final int IS_GLOBAL_SCOPE    = 1 << 3;

    
Is this block a synthetic one introduced by Parser?
/**
     * Is this block a synthetic one introduced by Parser?
     */
    public static final int IS_SYNTHETIC       = 1 << 4;

    
Is this the function body block? May not be the first, if parameter list contains expressions.
/**
     * Is this the function body block? May not be the first, if parameter list contains expressions.
     */
    public static final int IS_BODY            = 1 << 5;

    
Is this the parameter initialization block? If present, must be the first block, immediately wrapping the function body block.
/**
     * Is this the parameter initialization block? If present, must be the first block, immediately wrapping the function body block.
     */
    public static final int IS_PARAMETER_BLOCK = 1 << 6;

    
Marks the variable declaration block for case clauses of a switch statement.
/**
     * Marks the variable declaration block for case clauses of a switch statement.
     */
    public static final int IS_SWITCH_BLOCK    = 1 << 7;

    
Is this block tagged as breakable based on its contents
(block having labelled break statement)
/**
     * Is this block tagged as breakable based on its contents
     * (block having labelled break statement)
     */
    public static final int IS_BREAKABLE       = 1 << 8;

    
Constructor
Params:
token –      The first token of the block
finish –     The index of the last character
flags –      The flags of the block
statements – All statements in the block/**
     * Constructor
     *
     * @param token      The first token of the block
     * @param finish     The index of the last character
     * @param flags      The flags of the block
     * @param statements All statements in the block
     */
    public Block(final long token, final int finish, final int flags, final Statement... statements) {
        super(token, finish);

        this.statements = Arrays.asList(statements);
        this.symbols    = new LinkedHashMap<>();
        this.entryLabel = new Label("block_entry");
        this.breakLabel = new Label("block_break");
        final int len = statements.length;
        final int terminalFlags = len > 0 && statements[len - 1].hasTerminalFlags() ? IS_TERMINAL : 0;
        this.flags = terminalFlags | flags;
        this.conversion = null;
    }

    
Constructs a new block
Params:
token – The first token of the block
finish – The index of the last character
statements – All statements in the block/**
     * Constructs a new block
     *
     * @param token The first token of the block
     * @param finish The index of the last character
     * @param statements All statements in the block
     */
    public Block(final long token, final int finish, final Statement...statements){
        this(token, finish, IS_SYNTHETIC, statements);
    }

    
Constructs a new block
Params:
token – The first token of the block
finish – The index of the last character
statements – All statements in the block/**
     * Constructs a new block
     *
     * @param token The first token of the block
     * @param finish The index of the last character
     * @param statements All statements in the block
     */
    public Block(final long token, final int finish, final List<Statement> statements){
        this(token, finish, IS_SYNTHETIC, statements);
    }

    
Constructor
Params:
token –      The first token of the block
finish –     The index of the last character
flags –      The flags of the block
statements – All statements in the block/**
     * Constructor
     *
     * @param token      The first token of the block
     * @param finish     The index of the last character
     * @param flags      The flags of the block
     * @param statements All statements in the block
     */
    public Block(final long token, final int finish, final int flags, final List<Statement> statements) {
        this(token, finish, flags, statements.toArray(new Statement[0]));
    }

    private Block(final Block block, final int finish, final List<Statement> statements, final int flags, final Map<String, Symbol> symbols, final LocalVariableConversion conversion) {
        super(block, finish);
        this.statements = statements;
        this.flags      = flags;
        this.symbols    = new LinkedHashMap<>(symbols); //todo - symbols have no dependencies on any IR node and can as far as we understand it be shallow copied now
        this.entryLabel = new Label(block.entryLabel);
        this.breakLabel = new Label(block.breakLabel);
        this.conversion = conversion;
    }

    
Is this block the outermost eager global scope - i.e. the primordial program?
Used for global anchor point for scope depth computation for recompilation code
Returns:
true if outermost eager global scope/**
     * Is this block the outermost eager global scope - i.e. the primordial program?
     * Used for global anchor point for scope depth computation for recompilation code
     * @return true if outermost eager global scope
     */
    public boolean isGlobalScope() {
        return getFlag(IS_GLOBAL_SCOPE);
    }

    
Returns true if this block defines any symbols.
Returns:
true if this block defines any symbols./**
     * Returns true if this block defines any symbols.
     * @return true if this block defines any symbols.
     */
    public boolean hasSymbols() {
        return !symbols.isEmpty();
    }

    
Replaces symbols defined in this block with different symbols. Used to ensure symbol tables are
immutable upon construction and have copy-on-write semantics. Note that this method only replaces the
symbols in the symbol table, it does not act on any contained AST nodes that might reference the symbols.
Those should be updated separately as this method is meant to be used as part of such an update pass.
Params:
lc – the current lexical context
replacements – the map of symbol replacements
Returns:
a new block with replaced symbols, or this block if none of the replacements modified the symbol
table./**
     * Replaces symbols defined in this block with different symbols. Used to ensure symbol tables are
     * immutable upon construction and have copy-on-write semantics. Note that this method only replaces the
     * symbols in the symbol table, it does not act on any contained AST nodes that might reference the symbols.
     * Those should be updated separately as this method is meant to be used as part of such an update pass.
     * @param lc the current lexical context
     * @param replacements the map of symbol replacements
     * @return a new block with replaced symbols, or this block if none of the replacements modified the symbol
     * table.
     */
    public Block replaceSymbols(final LexicalContext lc, final Map<Symbol, Symbol> replacements) {
        if (symbols.isEmpty()) {
            return this;
        }
        final LinkedHashMap<String, Symbol> newSymbols = new LinkedHashMap<>(symbols);
        for (final Map.Entry<String, Symbol> entry: newSymbols.entrySet()) {
            final Symbol newSymbol = replacements.get(entry.getValue());
            assert newSymbol != null : "Missing replacement for " + entry.getKey();
            entry.setValue(newSymbol);
        }
        return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, newSymbols, conversion));
    }

    
Returns a copy of this block with a shallow copy of the symbol table.
Returns:
a copy of this block with a shallow copy of the symbol table./**
     * Returns a copy of this block with a shallow copy of the symbol table.
     * @return a copy of this block with a shallow copy of the symbol table.
     */
    public Block copyWithNewSymbols() {
        return new Block(this, finish, statements, flags, new LinkedHashMap<>(symbols), conversion);
    }

    @Override
    public Node ensureUniqueLabels(final LexicalContext lc) {
        return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
    }

    
Assist in IR navigation.
Params:
visitor – IR navigating visitor.
Returns:
new or same node/**
     * Assist in IR navigation.
     *
     * @param visitor IR navigating visitor.
     * @return new or same node
     */
    @Override
    public Node accept(final LexicalContext lc, final NodeVisitor<? extends LexicalContext> visitor) {
        if (visitor.enterBlock(this)) {
            return visitor.leaveBlock(setStatements(lc, Node.accept(visitor, statements)));
        }

        return this;
    }

    
Get a copy of the list for all the symbols defined in this block
Returns:
symbol iterator/**
     * Get a copy of the list for all the symbols defined in this block
     * @return symbol iterator
     */
    public List<Symbol> getSymbols() {
        return symbols.isEmpty() ? Collections.emptyList() : Collections.unmodifiableList(new ArrayList<>(symbols.values()));
    }

    
Retrieves an existing symbol defined in the current block.
Params:
name – the name of the symbol
Returns:
an existing symbol with the specified name defined in the current block, or null if this block doesn't
define a symbol with this name.T/**
     * Retrieves an existing symbol defined in the current block.
     * @param name the name of the symbol
     * @return an existing symbol with the specified name defined in the current block, or null if this block doesn't
     * define a symbol with this name.T
     */
    public Symbol getExistingSymbol(final String name) {
        return symbols.get(name);
    }

    
Test if this block represents a catch block in a try statement.
This is used by the Splitter as catch blocks are not be subject to splitting.
Returns:
true if this block represents a catch block in a try statement./**
     * Test if this block represents a <tt>catch</tt> block in a <tt>try</tt> statement.
     * This is used by the Splitter as catch blocks are not be subject to splitting.
     *
     * @return true if this block represents a catch block in a try statement.
     */
    public boolean isCatchBlock() {
        return statements.size() == 1 && statements.get(0) instanceof CatchNode;
    }

    @Override
    public void toString(final StringBuilder sb, final boolean printType) {
        for (final Node statement : statements) {
            statement.toString(sb, printType);
            sb.append(';');
        }
    }

    
Print symbols in block in alphabetical order, sorted on name
Used for debugging, see the --print-symbols flag
Params:
stream – print writer to output symbols to
Returns:
true if symbols were found/**
     * Print symbols in block in alphabetical order, sorted on name
     * Used for debugging, see the --print-symbols flag
     *
     * @param stream print writer to output symbols to
     *
     * @return true if symbols were found
     */
    public boolean printSymbols(final PrintWriter stream) {
        final List<Symbol> values = new ArrayList<>(symbols.values());

        Collections.sort(values, new Comparator<Symbol>() {
            @Override
            public int compare(final Symbol s0, final Symbol s1) {
                return s0.getName().compareTo(s1.getName());
            }
        });

        for (final Symbol symbol : values) {
            symbol.print(stream);
        }

        return !values.isEmpty();
    }

    
Tag block as terminal or non terminal
Params:
lc –          lexical context
isTerminal – is block terminal
Returns:
same block, or new if flag changed/**
     * Tag block as terminal or non terminal
     * @param lc          lexical context
     * @param isTerminal is block terminal
     * @return same block, or new if flag changed
     */
    public Block setIsTerminal(final LexicalContext lc, final boolean isTerminal) {
        return isTerminal ? setFlag(lc, IS_TERMINAL) : clearFlag(lc, IS_TERMINAL);
    }

    @Override
    public int getFlags() {
        return flags;
    }

    
Is this a terminal block, i.e. does it end control flow like ending with a throw or return?
Returns:
true if this node statement is terminal/**
     * Is this a terminal block, i.e. does it end control flow like ending with a throw or return?
     *
     * @return true if this node statement is terminal
     */
    @Override
    public boolean isTerminal() {
        return getFlag(IS_TERMINAL) && !getFlag(IS_BREAKABLE);
    }

    
Get the entry label for this block
Returns:
the entry label/**
     * Get the entry label for this block
     * @return the entry label
     */
    public Label getEntryLabel() {
        return entryLabel;
    }

    @Override
    public Label getBreakLabel() {
        return breakLabel;
    }

    @Override
    public Block setLocalVariableConversion(final LexicalContext lc, final LocalVariableConversion conversion) {
        if(this.conversion == conversion) {
            return this;
        }
        return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
    }

    @Override
    public LocalVariableConversion getLocalVariableConversion() {
        return conversion;
    }

    
Get the list of statements in this block
Returns:
a list of statements/**
     * Get the list of statements in this block
     *
     * @return a list of statements
     */
    public List<Statement> getStatements() {
        return Collections.unmodifiableList(statements);
    }

    
Returns the number of statements in the block.
Returns:
the number of statements in the block./**
     * Returns the number of statements in the block.
     * @return the number of statements in the block.
     */
    public int getStatementCount() {
        return statements.size();
    }

    
Returns the line number of the first statement in the block.
Returns:
the line number of the first statement in the block, or -1 if the block has no statements./**
     * Returns the line number of the first statement in the block.
     * @return the line number of the first statement in the block, or -1 if the block has no statements.
     */
    public int getFirstStatementLineNumber() {
        if(statements == null || statements.isEmpty()) {
            return -1;
        }
        return statements.get(0).getLineNumber();
    }

    
Returns the last statement in the block.
Returns:
the last statement in the block, or null if the block has no statements./**
     * Returns the last statement in the block.
     * @return the last statement in the block, or null if the block has no statements.
     */
    public Statement getLastStatement() {
        return statements.isEmpty() ? null : statements.get(statements.size() - 1);
    }

    
Reset the statement list for this block
Params:
lc – lexical context
statements – new statement list
Returns:
new block if statements changed, identity of statements == block.statements/**
     * Reset the statement list for this block
     *
     * @param lc lexical context
     * @param statements new statement list
     * @return new block if statements changed, identity of statements == block.statements
     */
    public Block setStatements(final LexicalContext lc, final List<Statement> statements) {
        if (this.statements == statements) {
            return this;
        }
        int lastFinish = 0;
        if (!statements.isEmpty()) {
            lastFinish = statements.get(statements.size() - 1).getFinish();
        }
        return Node.replaceInLexicalContext(lc, this, new Block(this, Math.max(finish, lastFinish), statements, flags, symbols, conversion));
    }

    
Add or overwrite an existing symbol in the block
Params:
symbol – symbol/**
     * Add or overwrite an existing symbol in the block
     *
     * @param symbol symbol
     */
    public void putSymbol(final Symbol symbol) {
        symbols.put(symbol.getName(), symbol);
    }

    
Check whether scope is necessary for this Block
Returns:
true if this function needs a scope/**
     * Check whether scope is necessary for this Block
     *
     * @return true if this function needs a scope
     */
    public boolean needsScope() {
        return (flags & NEEDS_SCOPE) == NEEDS_SCOPE;
    }

    
Check whether this block is synthetic or not.
Returns:
true if this is a synthetic block/**
     * Check whether this block is synthetic or not.
     *
     * @return true if this is a synthetic block
     */
    public boolean isSynthetic() {
        return (flags & IS_SYNTHETIC) == IS_SYNTHETIC;
    }

    @Override
    public Block setFlags(final LexicalContext lc, final int flags) {
        if (this.flags == flags) {
            return this;
        }
        return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
    }

    @Override
    public Block clearFlag(final LexicalContext lc, final int flag) {
        return setFlags(lc, flags & ~flag);
    }

    @Override
    public Block setFlag(final LexicalContext lc, final int flag) {
        return setFlags(lc, flags | flag);
    }

    @Override
    public boolean getFlag(final int flag) {
        return (flags & flag) == flag;
    }

    
Set the needs scope flag.
Params:
lc – lexicalContext
Returns:
new block if state changed, otherwise this/**
     * Set the needs scope flag.
     * @param lc lexicalContext
     * @return new block if state changed, otherwise this
     */
    public Block setNeedsScope(final LexicalContext lc) {
        if (needsScope()) {
            return this;
        }

        return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags | NEEDS_SCOPE, symbols, conversion));
    }

    
Computationally determine the next slot for this block,
indexed from 0. Use this as a relative base when computing
frames
Returns:
next slot/**
     * Computationally determine the next slot for this block,
     * indexed from 0. Use this as a relative base when computing
     * frames
     * @return next slot
     */
    public int nextSlot() {
        int next = 0;
        for (final Symbol symbol : getSymbols()) {
            if (symbol.hasSlot()) {
                next += symbol.slotCount();
            }
        }
        return next;
    }

    
Determine whether this block needs to provide its scope object creator for use by its child nodes.
This is only necessary for synthetic parent blocks of for-in loops with lexical declarations.
See Also:
needsScopeCreator.needsScopeCreator()
Returns:
true if child nodes need access to this block's scope creator/**
     * Determine whether this block needs to provide its scope object creator for use by its child nodes.
     * This is only necessary for synthetic parent blocks of for-in loops with lexical declarations.
     *
     * @see ForNode#needsScopeCreator()
     * @return true if child nodes need access to this block's scope creator
     */
    public boolean providesScopeCreator() {
        return needsScope() && isSynthetic()
                && (getLastStatement() instanceof ForNode)
                && ((ForNode) getLastStatement()).needsScopeCreator();
    }

    @Override
    public boolean isBreakableWithoutLabel() {
        return false;
    }

    @Override
    public List<Label> getLabels() {
        return Collections.unmodifiableList(Arrays.asList(entryLabel, breakLabel));
    }

    @Override
    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
        return Acceptor.accept(this, visitor);
    }

    
Checks if this is a function body.
Returns:
true if the function body flag is set/**
     * Checks if this is a function body.
     *
     * @return true if the function body flag is set
     */
    public boolean isFunctionBody() {
        return getFlag(IS_BODY);
    }

    
Checks if this is a parameter block.
Returns:
true if the parameter block flag is set/**
     * Checks if this is a parameter block.
     *
     * @return true if the parameter block flag is set
     */
    public boolean isParameterBlock() {
        return getFlag(IS_PARAMETER_BLOCK);
    }

    
Checks whether this is a switch block.
Returns:
true if this is a switch block/**
     * Checks whether this is a switch block.
     *
     * @return true if this is a switch block
     */
    public boolean isSwitchBlock() {
        return getFlag(IS_SWITCH_BLOCK);
    }
}