mirror of https://github.com/odrling/Aegisub
368 lines
9.8 KiB
C++
368 lines
9.8 KiB
C++
/**********************************************
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License: BSD
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Project Webpage: http://cajun-jsonapi.sourceforge.net/
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Author: Terry Caton
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***********************************************/
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#include "libaegisub/cajun/reader.h"
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#include <cassert>
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#include <set>
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#include <sstream>
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/*
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TODO:
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* better documentation
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* unicode character decoding
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*/
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namespace json {
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std::istream& operator >> (std::istream& istr, UnknownElement& elementRoot) {
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Reader::Read(elementRoot, istr);
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return istr;
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}
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/// Wrapper around istream to keep track of document/line offsets
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class Reader::InputStream {
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std::istream& m_iStr;
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Location m_Location;
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public:
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InputStream(std::istream& iStr) : m_iStr(iStr) { }
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int Get() {
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assert(!m_iStr.eof());
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int c = m_iStr.get();
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++m_Location.m_nDocOffset;
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if (c == '\n') {
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++m_Location.m_nLine;
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m_Location.m_nLineOffset = 0;
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}
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else {
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++m_Location.m_nLineOffset;
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}
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return c;
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}
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int Peek() {
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assert(!m_iStr.eof());
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return m_iStr.peek();
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}
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bool EOS() {
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// libc++ doesn't set eof when a peek fails
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return m_iStr.peek() == EOF || m_iStr.eof();
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}
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Location const& GetLocation() const { return m_Location; }
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};
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class Reader::TokenStream {
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Tokens const& m_Tokens;
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Tokens::const_iterator m_itCurrent;
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public:
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TokenStream(Tokens const& tokens) : m_Tokens(tokens), m_itCurrent(tokens.begin())
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{ }
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Token const& Peek() {
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assert(!EOS());
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return *m_itCurrent;
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}
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Token const& Get() {
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assert(!EOS());
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return *m_itCurrent++;
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}
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bool EOS() const { return m_itCurrent == m_Tokens.end(); }
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};
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void Reader::Read(UnknownElement& unknown, std::istream& istr) {
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Reader reader;
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Tokens tokens;
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InputStream inputStream(istr);
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reader.Scan(tokens, inputStream);
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TokenStream tokenStream(tokens);
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unknown = reader.Parse(tokenStream);
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if (!tokenStream.EOS()) {
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Token const& token = tokenStream.Peek();
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throw ParseException("Expected End of token stream; found " + token.sValue, token.locBegin, token.locEnd);
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}
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}
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void Reader::Scan(Tokens& tokens, InputStream& inputStream) {
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while (EatWhiteSpace(inputStream), !inputStream.EOS()) {
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// if all goes well, we'll create a token each pass
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Token token;
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token.locBegin = inputStream.GetLocation();
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// gives us null-terminated string
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std::string sChar;
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sChar.push_back(inputStream.Peek());
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switch (sChar[0]) {
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case '{':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_OBJECT_BEGIN;
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break;
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case '}':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_OBJECT_END;
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break;
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case '[':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_ARRAY_BEGIN;
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break;
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case ']':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_ARRAY_END;
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break;
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case ',':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_NEXT_ELEMENT;
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break;
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case ':':
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token.sValue = sChar[0];
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MatchExpectedString(sChar, inputStream);
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token.nType = Token::TOKEN_MEMBER_ASSIGN;
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break;
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case '"':
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MatchString(token.sValue, inputStream);
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token.nType = Token::TOKEN_STRING;
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break;
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case '-':
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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case '8':
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case '9':
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MatchNumber(token.sValue, inputStream);
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token.nType = Token::TOKEN_NUMBER;
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break;
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case 't':
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token.sValue = "true";
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MatchExpectedString(token.sValue, inputStream);
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token.nType = Token::TOKEN_BOOLEAN;
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break;
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case 'f':
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token.sValue = "false";
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MatchExpectedString(token.sValue, inputStream);
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token.nType = Token::TOKEN_BOOLEAN;
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break;
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case 'n':
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token.sValue = "null";
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MatchExpectedString(token.sValue, inputStream);
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token.nType = Token::TOKEN_NULL;
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break;
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default:
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throw ScanException("Unexpected character in stream: " + sChar, inputStream.GetLocation());
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}
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token.locEnd = inputStream.GetLocation();
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tokens.push_back(token);
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}
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}
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void Reader::EatWhiteSpace(InputStream& inputStream) {
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while (!inputStream.EOS() && ::isspace(inputStream.Peek()))
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inputStream.Get();
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}
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void Reader::MatchExpectedString(std::string const& sExpected, InputStream& inputStream) {
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std::string::const_iterator it(sExpected.begin()), itEnd(sExpected.end());
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for ( ; it != itEnd; ++it) {
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if (inputStream.EOS() || // did we reach the end before finding what we're looking for...
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inputStream.Get() != *it) // ...or did we find something different?
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{
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throw ScanException("Expected string: " + sExpected, inputStream.GetLocation());
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}
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}
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}
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void Reader::MatchString(std::string& string, InputStream& inputStream) {
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MatchExpectedString("\"", inputStream);
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while (!inputStream.EOS() && inputStream.Peek() != '"') {
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char c = inputStream.Get();
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// escape?
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if (c == '\\' && !inputStream.EOS()) { // shouldn't have reached the end yet
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c = inputStream.Get();
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switch (c) {
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case '/': string.push_back('/'); break;
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case '"': string.push_back('"'); break;
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case '\\': string.push_back('\\'); break;
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case 'b': string.push_back('\b'); break;
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case 'f': string.push_back('\f'); break;
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case 'n': string.push_back('\n'); break;
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case 'r': string.push_back('\r'); break;
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case 't': string.push_back('\t'); break;
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case 'u': // TODO: what do we do with this?
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default:
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throw ScanException(std::string("Unrecognized escape sequence found in string: \\") + c, inputStream.GetLocation());
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}
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}
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else {
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string.push_back(c);
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}
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}
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// eat the last '"' that we hopefully just peeked
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MatchExpectedString("\"", inputStream);
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}
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void Reader::MatchNumber(std::string& sNumber, InputStream& inputStream) {
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const char sNumericChars[] = "0123456789.eE-+";
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std::set<char> numericChars;
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numericChars.insert(sNumericChars, sNumericChars + sizeof(sNumericChars));
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while (!inputStream.EOS()&& numericChars.count(inputStream.Peek()))
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sNumber.push_back(inputStream.Get());
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}
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UnknownElement Reader::Parse(Reader::TokenStream& tokenStream) {
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if (tokenStream.EOS())
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throw ParseException("Unexpected end of token stream", Location(), Location()); // nowhere to point to
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Token const& token = tokenStream.Peek();
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switch (token.nType) {
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case Token::TOKEN_OBJECT_BEGIN: return ParseObject(tokenStream);
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case Token::TOKEN_ARRAY_BEGIN: return ParseArray(tokenStream);
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case Token::TOKEN_STRING: return ParseString(tokenStream);
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case Token::TOKEN_NUMBER: return ParseNumber(tokenStream);
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case Token::TOKEN_BOOLEAN: return ParseBoolean(tokenStream);
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case Token::TOKEN_NULL: return ParseNull(tokenStream);
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default:
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throw ParseException("Unexpected token: " + token.sValue, token.locBegin, token.locEnd);
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}
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}
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UnknownElement Reader::ParseObject(Reader::TokenStream& tokenStream) {
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MatchExpectedToken(Token::TOKEN_OBJECT_BEGIN, tokenStream);
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Object object;
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while (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_OBJECT_END) {
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// first the member name. save the token in case we have to throw an exception
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Token const& tokenName = tokenStream.Peek();
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std::string const& name = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
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if (object.count(name))
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throw ParseException("Duplicate object member token: " + name, tokenName.locBegin, tokenName.locEnd);
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// ...then the key/value separator...
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MatchExpectedToken(Token::TOKEN_MEMBER_ASSIGN, tokenStream);
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// ...then the value itself (can be anything).
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object[name] = Parse(tokenStream);
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if (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_OBJECT_END)
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MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
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}
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MatchExpectedToken(Token::TOKEN_OBJECT_END, tokenStream);
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return object;
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}
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UnknownElement Reader::ParseArray(Reader::TokenStream& tokenStream) {
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MatchExpectedToken(Token::TOKEN_ARRAY_BEGIN, tokenStream);
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Array array;
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while (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_ARRAY_END)
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{
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array.push_back(Parse(tokenStream));
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if (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_ARRAY_END)
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MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
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}
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MatchExpectedToken(Token::TOKEN_ARRAY_END, tokenStream);
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return array;
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}
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UnknownElement Reader::ParseString(Reader::TokenStream& tokenStream) {
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return MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
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}
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UnknownElement Reader::ParseNumber(Reader::TokenStream& tokenStream) {
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Token const& currentToken = tokenStream.Peek(); // might need this later for throwing exception
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std::string const& sValue = MatchExpectedToken(Token::TOKEN_NUMBER, tokenStream);
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// First try to parse it as an int
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std::istringstream iStr(sValue);
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int64_t iValue;
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iStr >> iValue;
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// If the entire token was consumed then it's not a double
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if (iStr.eof())
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return iValue;
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// Try again as a double
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iStr.seekg(0, std::ios::beg);
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double dValue;
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iStr >> dValue;
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// If there's still stuff left in the token then it's malformed
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if (!iStr.eof())
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throw ParseException(std::string("Unexpected character in NUMBER token: ") + (char)iStr.peek(),
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currentToken.locBegin, currentToken.locEnd);
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return dValue;
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}
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UnknownElement Reader::ParseBoolean(Reader::TokenStream& tokenStream) {
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return MatchExpectedToken(Token::TOKEN_BOOLEAN, tokenStream) == "true";
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}
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UnknownElement Reader::ParseNull(Reader::TokenStream& tokenStream) {
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MatchExpectedToken(Token::TOKEN_NULL, tokenStream);
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return Null();
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}
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std::string const& Reader::MatchExpectedToken(Token::Type nExpected, Reader::TokenStream& tokenStream) {
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if (tokenStream.EOS())
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throw ParseException("Unexpected End of token stream", Location(), Location()); // nowhere to point to
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Token const& token = tokenStream.Get();
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if (token.nType != nExpected)
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throw ParseException("Unexpected token: " + token.sValue, token.locBegin, token.locEnd);
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return token.sValue;
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}
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}
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