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Parsodus
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Removed left and rightmost character from variables/terminals

This commit is contained in:
kwullaer 2017-01-25 10:52:19 +01:00
parent 0983467774
commit d609b69eb4
1 changed files with 44 additions and 5 deletions
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49
src/inputparser.cpp
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@ -8,14 +8,14 @@ namespace pds {
const char* InputParserException::what() const throw() {
return m_what.c_str();
}
Config InputParser::parseInput(std::istream& is) {
Config InputParser::parseInput(std::istream& is) {
ParsodusLexer lex(is);
Config config;
bool readingTerminals = false;
bool readingGrammar = false;
bool readingPrecedences = false;
try {
while(true) {
@ -51,9 +51,15 @@ namespace pds {
lexColon(lex, token, false);
readingGrammar = true;
break;
/**/
case ParsodusLexer::PRECEDENCES:
lexColon(lex, token, false);
readingPrecedences = true;
break;
/**/
case ParsodusLexer::TERMINAL:
if(readingTerminals) {
config.grammar.terminals.insert(token.content);
config.grammar.terminals.insert(token.content.substr(1, token.content.size - 1));
} else {
throw InputParserException("Found a terminal outside a grammar or terminals section: " + token.content);
}
@ -62,12 +68,12 @@ namespace pds {
lexColon(lex, token);
if(token.type != ParsodusLexer::VARIABLE)
throw InputParserException("Expected to find a start variable, but found: " + token.content);
config.grammar.start = token.content;
config.grammar.start = token.content.substr(1, token.content.size - 1);
break;
case ParsodusLexer::VARIABLE:
if(readingGrammar) {
if(config.grammar.variables.find(token.content) == config.grammar.variables.end())
config.grammar.variables.insert(token.content);
config.grammar.variables.insert(token.content.substr(1, token.content.size - 1));
std::string current_head = token.content;
// Parsing rule
@ -79,6 +85,7 @@ namespace pds {
bool parsing_head = true;
while(parsing_head) {
token = lex.nextToken();
token.content = token.content.substr(1, token.content.size - 1);
switch(token.type) {
case ParsodusLexer::VARIABLE:
rule->tail.push_back(token.content);
@ -100,6 +107,38 @@ namespace pds {
} else
throw InputParserException("Found a variable outside a grammar section: " + token.content);
break;
/**/
case ParsodusLexer::PRECEDENCE:
if (readingPrecedences) {
pds::PrecedenceType precedence_type;
switch(token.content) {
case "left":
precedence_type = pds::PrecedenceType::LEFT;
break;
case "nonassoc":
precedence_type = pds::PrecedenceType::NONASSOC;
break;
case "right":
precedence_type = pds::PrecedenceType::RIGHT;
break;
}
int counter = 0;
while (true) {
token = lex.nextToken();
if (token.type == ParsodusLexer::SEMICOLON)
break;
if (token.type != ParsodusLexer::TERMINAL)
throw InputParserException("Expecting to find a terminal, but found '" + token.content + "' instead'");
if (config.grammar.precedence.find(token.type) == config.grammar.precedence)
throw InputParserException("Found same terminal in multiple precedence rules");
config.grammar.precedence.insert(make_pair(token.content.substr(1, token.content.size - 1), make_pair(counter++, precedence_type)));
}
} else
throw InputParserException("Found a precedence rule outside a precedence section: " + token.content);
/**/
default:
break;