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#include "antlr/TokenStreamSelector.hpp"
#include "antlr/TokenStreamRetryException.hpp"
ANTLR_BEGIN_NAMESPACE(antlr)
/** A token stream MUX (multiplexor) knows about n token streams
* and can multiplex them onto the same channel for use by token
* stream consumer like a parser. This is a way to have multiple
* lexers break up the same input stream for a single parser.
* Or, you can have multiple instances of the same lexer handle
* multiple input streams; this works great for includes.
*/
TokenStreamSelector::TokenStreamSelector()
: input(0)
{
}
TokenStreamSelector::~TokenStreamSelector()
{
}
void TokenStreamSelector::addInputStream(TokenStream* stream, const ANTLR_USE_NAMESPACE(std)string& key)
{
inputStreamNames[key] = stream;
}
TokenStream* TokenStreamSelector::getCurrentStream() const
{
return input;
}
TokenStream* TokenStreamSelector::getStream(const ANTLR_USE_NAMESPACE(std)string& sname) const
{
inputStreamNames_coll::const_iterator i = inputStreamNames.find(sname);
if (i == inputStreamNames.end()) {
throw ANTLR_USE_NAMESPACE(std)string("TokenStream ")+sname+" not found";
}
return (*i).second;
}
RefToken TokenStreamSelector::nextToken()
{
// keep looking for a token until you don't
// get a retry exception
for (;;) {
try {
return input->nextToken();
}
catch (TokenStreamRetryException& r) {
// just retry "forever"
}
}
}
TokenStream* TokenStreamSelector::pop()
{
TokenStream* stream = streamStack.top();
streamStack.pop();
select(stream);
return stream;
}
void TokenStreamSelector::push(TokenStream* stream)
{
streamStack.push(input);
select(stream);
}
void TokenStreamSelector::push(const ANTLR_USE_NAMESPACE(std)string& sname)
{
streamStack.push(input);
select(sname);
}
void TokenStreamSelector::retry()
{
throw TokenStreamRetryException();
}
/** Set the stream without pushing old stream */
void TokenStreamSelector::select(TokenStream* stream)
{
input = stream;
}
void TokenStreamSelector::select(const ANTLR_USE_NAMESPACE(std)string& sname)
{
inputStreamNames_coll::const_iterator i = inputStreamNames.find(sname);
if (i == inputStreamNames.end()) {
throw ANTLR_USE_NAMESPACE(std)string("TokenStream ")+sname+" not found";
}
input = (*i).second;
}
ANTLR_END_NAMESPACE
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