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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/* $Rev$ $Date$ */
#ifndef tuscany_eval_read_hpp
#define tuscany_eval_read_hpp
/**
* Script evaluator read functions.
*/
#include <iostream>
#include <string>
#include <sstream>
#include <ctype.h>
#include "list.hpp"
#include "value.hpp"
#include "primitive.hpp"
namespace tuscany
{
const value rightParenthesis(makeList<value>(")"));
const value leftParenthesis(makeList<value>("("));
const value comment(makeList<value>(";"));
const double stringToNumber(const std::string& str) {
double d;
std::istringstream is(str);
is >> d;
return d;
}
const bool isWhitespace(const char ch) {
return ch != -1 && isspace(ch);
}
const bool isIdentifierStart(const char ch) {
return ch != -1 && !isspace(ch) && !isdigit(ch);
}
const bool isIdentifierPart(const char ch) {
return ch != -1 && !isspace(ch) && ch != '(' && ch != ')';
}
const bool isDigit(const char ch) {
return isdigit(ch) || ch == '.';
}
const bool isLeftParenthesis(const value& token) {
return leftParenthesis == token;
}
const bool isRightParenthesis(const value& token) {
return rightParenthesis == token;
}
const char readChar(std::istream& in) {
if(in.eof()) {
return -1;
}
char c = in.get();
return c;
}
const char peekChar(std::istream& in) {
if(in.eof())
return -1;
char c = in.peek();
return c;
}
const bool isQuote(const value& token) {
return token == quoteSymbol;
}
const value readQuoted(std::istream& in);
const value readIdentifier(const char chr, std::istream& in);
const value readString(const char chr, std::istream& in);
const value readNumber(const char chr, std::istream& in);
const value read(std::istream& in);
const value readToken(std::istream& in) {
const char firstChar = readChar(in);
if(isWhitespace(firstChar))
return readToken(in);
if(firstChar == '\'')
return readQuoted(in);
if(firstChar == '(')
return leftParenthesis;
if(firstChar == ')')
return rightParenthesis;
if(firstChar == '"')
return readString(firstChar, in);
if(isIdentifierStart(firstChar))
return readIdentifier(firstChar, in);
if(isDigit(firstChar))
return readNumber(firstChar, in);
if(firstChar == -1)
return value();
std::cout << "Illegal lexical syntax '" << firstChar << "'" << "\n";
return readToken(in);
}
const value readQuoted(std::istream& in) {
return makeList(quoteSymbol, read(in));
}
const list<value> readList(const list<value>& listSoFar, std::istream& in) {
const value token = readToken(in);
if(isNil(token) || isRightParenthesis(token))
return reverse(listSoFar);
if(isLeftParenthesis(token))
return readList(cons(value(readList(list<value> (), in)), listSoFar), in);
return readList(cons(token, listSoFar), in);
}
const std::string listToString(const list<char>& l) {
if(l == list<char> ())
return "";
return car(l) + listToString(cdr(l));
}
const list<char> readIdentifierHelper(const list<char>& listSoFar, std::istream& in) {
const char nextChar = peekChar(in);
if(isIdentifierPart(nextChar))
return readIdentifierHelper(cons(readChar(in), listSoFar), in);
return reverse(listSoFar);
}
const value readIdentifier(const char chr, std::istream& in) {
return listToString(readIdentifierHelper(makeList(chr), in)).c_str();
}
const list<char> readStringHelper(const list<char>& listSoFar, std::istream& in) {
const char nextChar = readChar(in);
if(nextChar != -1 && nextChar != '"')
return readStringHelper(cons(nextChar, listSoFar), in);
return reverse(listSoFar);
}
const value readString(const char chr, std::istream& in) {
return listToString(readStringHelper(list<char>(), in));
}
const list<char> readNumberHelper(const list<char>& listSoFar, std::istream& in) {
const char nextChar = peekChar(in);
if(isDigit(nextChar))
return readNumberHelper(cons(readChar(in), listSoFar), in);
return reverse(listSoFar);
}
const value readNumber(const char chr, std::istream& in) {
return stringToNumber(listToString(readNumberHelper(makeList(chr), in)));
}
const value read(std::istream& in) {
const value nextToken = readToken(in);
if(isLeftParenthesis(nextToken))
return readList(list<value> (), in);
return nextToken;
}
}
#endif /* tuscany_eval_read_hpp */
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