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StringTemplate is a java template engine for generating source code, web pages, emails, or any other formatted text output. StringTemplate is particularly good at multi-targeted code generators, multiple site skins, and internationalization/localization. It evolved over years of effort developing jGuru.com. StringTemplate also powers the ANTLR 3 and 4 code generator. Its distinguishing characteristic is that unlike other engines, it strictly enforces model-view separation. Strict separation makes websites and code generators more flexible and maintainable; it also provides an excellent defense against malicious template authors.

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/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.stringtemplate.v4.compiler;

import org.antlr.runtime.*;
import org.antlr.runtime.tree.CommonTree;
import org.stringtemplate.v4.Interpreter;
import org.stringtemplate.v4.misc.*;

/** Temporary data used during construction and functions that fill it / use it.
 *  Result is {@link #impl} {@link CompiledST} object.
 */
public class CompilationState {
	/** The compiled code implementation to fill in. */
	CompiledST impl = new CompiledST();

	/** Track unique strings; copy into {@link CompiledST#strings} after compilation. */
	StringTable stringtable = new StringTable();

	/**
	 * Track instruction location within
	 * {@code impl.}{@link CompiledST#instrs instrs} array; this is next address
	 * to write to. Byte-addressable memory.
	 */
	int ip = 0;

	TokenStream tokens;

	ErrorManager errMgr;

	public CompilationState(ErrorManager errMgr, String name, TokenStream tokens) {
		this.errMgr = errMgr;
		this.tokens = tokens;
		impl.name = name;
		impl.prefix = Misc.getPrefix(name);
	}

	public int defineString(String s) { return stringtable.add(s); }

	public void refAttr(Token templateToken, CommonTree id) {
		String name = id.getText();
		if ( impl.formalArguments!=null && impl.formalArguments.get(name)!=null ) {
			FormalArgument arg = impl.formalArguments.get(name);
			int index = arg.index;
			emit1(id, Bytecode.INSTR_LOAD_LOCAL, index);
		}
		else {
			if ( Interpreter.predefinedAnonSubtemplateAttributes.contains(name) ) {
				errMgr.compileTimeError(ErrorType.REF_TO_IMPLICIT_ATTRIBUTE_OUT_OF_SCOPE,
										templateToken, id.token);
				emit(id, Bytecode.INSTR_NULL);
			}
			else {
				emit1(id, Bytecode.INSTR_LOAD_ATTR, name);
			}
		}
	}

	public void setOption(CommonTree id) {
		Interpreter.Option O = Compiler.supportedOptions.get(id.getText());
		emit1(id, Bytecode.INSTR_STORE_OPTION, O.ordinal());
	}

	public void func(Token templateToken, CommonTree id) {
		Short funcBytecode = Compiler.funcs.get(id.getText());
		if ( funcBytecode==null ) {
			errMgr.compileTimeError(ErrorType.NO_SUCH_FUNCTION, templateToken, id.token);
			emit(id, Bytecode.INSTR_POP);
		}
		else {
			emit(id, funcBytecode);
		}
	}

	public void emit(short opcode) { emit(null,opcode); }

	public void emit(CommonTree opAST, short opcode) {
		ensureCapacity(1);
		if ( opAST!=null ) {
			int i = opAST.getTokenStartIndex();
			int j = opAST.getTokenStopIndex();
			int p = ((CommonToken)tokens.get(i)).getStartIndex();
			int q = ((CommonToken)tokens.get(j)).getStopIndex();
			if ( !(p<0 || q<0) ) impl.sourceMap[ip] = new Interval(p, q);
		}
		impl.instrs[ip++] = (byte)opcode;
	}

	public void emit1(CommonTree opAST, short opcode, int arg) {
		emit(opAST, opcode);
		ensureCapacity(Bytecode.OPND_SIZE_IN_BYTES);
		writeShort(impl.instrs, ip, (short)arg);
		ip += Bytecode.OPND_SIZE_IN_BYTES;
	}

	public void emit2(CommonTree opAST, short opcode, int arg, int arg2) {
		emit(opAST, opcode);
		ensureCapacity(Bytecode.OPND_SIZE_IN_BYTES * 2);
		writeShort(impl.instrs, ip, (short)arg);
		ip += Bytecode.OPND_SIZE_IN_BYTES;
		writeShort(impl.instrs, ip, (short)arg2);
		ip += Bytecode.OPND_SIZE_IN_BYTES;
	}

	public void emit2(CommonTree opAST, short opcode, String s, int arg2) {
		int i = defineString(s);
		emit2(opAST, opcode, i, arg2);
	}

	public void emit1(CommonTree opAST, short opcode, String s) {
		int i = defineString(s);
		emit1(opAST, opcode, i);
	}

	public void insert(int addr, short opcode, String s) {
		//System.out.println("before insert of "+opcode+"("+s+"):"+ Arrays.toString(impl.instrs));
		ensureCapacity(1+Bytecode.OPND_SIZE_IN_BYTES);
		int instrSize = 1 + Bytecode.OPND_SIZE_IN_BYTES;
		System.arraycopy(impl.instrs, addr,
						 impl.instrs, addr + instrSize,
						 ip-addr); // make room for opcode, opnd
		int save = ip;
		ip = addr;
		emit1(null,opcode, s);
		ip = save+instrSize;
		//System.out.println("after  insert of "+opcode+"("+s+"):"+ Arrays.toString(impl.instrs));
		// adjust addresses for BR and BRF
		int a=addr+instrSize;
		while ( a < ip ) {
			byte op = impl.instrs[a];
			Bytecode.Instruction I = Bytecode.instructions[op];
			if ( op == Bytecode.INSTR_BR || op == Bytecode.INSTR_BRF ) {
				int opnd = BytecodeDisassembler.getShort(impl.instrs, a+1);
				writeShort(impl.instrs, a+1, (short)(opnd+instrSize));
			}
			a += I.nopnds * Bytecode.OPND_SIZE_IN_BYTES + 1;
		}
		//System.out.println("after  insert of "+opcode+"("+s+"):"+ Arrays.toString(impl.instrs));
	}

	public void write(int addr, short value) {
		writeShort(impl.instrs, addr, value);
	}

	protected void ensureCapacity(int n) {
		if ( (ip+n) >= impl.instrs.length ) { // ensure room for full instruction
			byte[] c = new byte[impl.instrs.length*2];
			System.arraycopy(impl.instrs, 0, c, 0, impl.instrs.length);
			impl.instrs = c;
			Interval[] sm = new Interval[impl.sourceMap.length*2];
			System.arraycopy(impl.sourceMap, 0, sm, 0, impl.sourceMap.length);
			impl.sourceMap = sm;
		}
	}

	public void indent(CommonTree indent) {
		emit1(indent,Bytecode.INSTR_INDENT, indent.getText());
	}

	/** Write value at index into a byte array highest to lowest byte,
	 *  left to right.
	 */
	public static void writeShort(byte[] memory, int index, short value) {
		memory[index+0] = (byte)((value>>(8*1))&0xFF);
		memory[index+1] = (byte)(value&0xFF);
	}
}