Scan.h

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//
// Copyright (C) 2002-2005 3Dlabs Inc. Ltd.
// Copyright (C) 2013 LunarG, Inc.
//
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#ifndef _GLSLANG_SCAN_INCLUDED_
#define _GLSLANG_SCAN_INCLUDED_

#include "Versions.h"

namespace glslang {

// Use a global end-of-input character, so no translation is needed across
// layers of encapsulation. Characters are all 8 bit, and positive, so there is
// no aliasing of character 255 onto -1, for example.
const int EndOfInput = -1;

//
// A character scanner that seamlessly, on read-only strings, reads across an
// array of strings without assuming null termination.
//
class TInputScanner {
public:
 TInputScanner(int n, const char* const s[], size_t L[], const char* const* names = nullptr,
 int b = 0, int f = 0, bool single = false) :
 numSources(n),
 // up to this point, common usage is "char*", but now we need positive 8-bit characters
 sources(reinterpret_cast<const unsigned char* const *>(s)),
 lengths(L), currentSource(0), currentChar(0), stringBias(b), finale(f), singleLogical(single),
 endOfFileReached(false)
 {
 loc = new TSourceLoc[numSources];
 for (int i = 0; i < numSources; ++i) {
 loc[i].init(i - stringBias);
 }
 if (names != nullptr) {
 for (int i = 0; i < numSources; ++i)
 loc[i].name = names[i];
 }
 loc[currentSource].line = 1;
 logicalSourceLoc.init(1);
 logicalSourceLoc.name = loc[0].name;
 }

 virtual ~TInputScanner()
 {
 delete [] loc;
 }

 // retrieve the next character and advance one character
 int get()
 {
 int ret = peek();
 if (ret == EndOfInput)
 return ret;
 ++loc[currentSource].column;
 ++logicalSourceLoc.column;
 if (ret == '\n') {
 ++loc[currentSource].line;
 ++logicalSourceLoc.line;
 logicalSourceLoc.column = 0;
 loc[currentSource].column = 0;
 }
 advance();

 return ret;
 }

 // retrieve the next character, no advance
 int peek()
 {
 if (currentSource >= numSources) {
 endOfFileReached = true;
 return EndOfInput;
 }
 // Make sure we do not read off the end of a string.
 // N.B. Sources can have a length of 0.
 int sourceToRead = currentSource;
 size_t charToRead = currentChar;
 while(charToRead >= lengths[sourceToRead]) {
 charToRead = 0;
 sourceToRead += 1;
 if (sourceToRead >= numSources) {
 return EndOfInput;
 }
 }

 // Here, we care about making negative valued characters positive
 return sources[sourceToRead][charToRead];
 }

 // go back one character
 void unget()
 {
 // Do not roll back once we've reached the end of the file.
 if (endOfFileReached)
 return;

 if (currentChar > 0) {
 --currentChar;
 --loc[currentSource].column;
 --logicalSourceLoc.column;
 if (loc[currentSource].column < 0) {
 // We've moved back past a new line. Find the
 // previous newline (or start of the file) to compute
 // the column count on the now current line.
 size_t chIndex = currentChar;
 while (chIndex > 0) {
 if (sources[currentSource][chIndex] == '\n') {
 break;
 }
 --chIndex;
 }
 logicalSourceLoc.column = (int)(currentChar - chIndex);
 loc[currentSource].column = (int)(currentChar - chIndex);
 }
 } else {
 do {
 --currentSource;
 } while (currentSource > 0 && lengths[currentSource] == 0);
 if (lengths[currentSource] == 0) {
 // set to 0 if we've backed up to the start of an empty string
 currentChar = 0;
 } else
 currentChar = lengths[currentSource] - 1;
 }
 if (peek() == '\n') {
 --loc[currentSource].line;
 --logicalSourceLoc.line;
 }
 }

 // for #line override
 void setLine(int newLine)
 {
 logicalSourceLoc.line = newLine;
 loc[getLastValidSourceIndex()].line = newLine;
 }

 // for #line override in filename based parsing
 void setFile(const char* filename)
 {
 logicalSourceLoc.name = filename;
 loc[getLastValidSourceIndex()].name = filename;
 }

 void setFile(const char* filename, int i)
 {
 if (i == getLastValidSourceIndex()) {
 logicalSourceLoc.name = filename;
 }
 loc[i].name = filename;
 }

 void setString(int newString)
 {
 logicalSourceLoc.string = newString;
 loc[getLastValidSourceIndex()].string = newString;
 logicalSourceLoc.name = nullptr;
 loc[getLastValidSourceIndex()].name = nullptr;
 }

 // for #include content indentation
 void setColumn(int col)
 {
 logicalSourceLoc.column = col;
 loc[getLastValidSourceIndex()].column = col;
 }

 void setEndOfInput()
 {
 endOfFileReached = true;
 currentSource = numSources;
 }

 bool atEndOfInput() const { return endOfFileReached; }

 const TSourceLoc& getSourceLoc() const
 {
 if (singleLogical) {
 return logicalSourceLoc;
 } else {
 return loc[std::max(0, std::min(currentSource, numSources - finale - 1))];
 }
 }
 // Returns the index (starting from 0) of the most recent valid source string we are reading from.
 int getLastValidSourceIndex() const { return std::min(currentSource, numSources - 1); }

 void consumeWhiteSpace(bool& foundNonSpaceTab);
 bool consumeComment();
 void consumeWhitespaceComment(bool& foundNonSpaceTab);
 bool scanVersion(int& version, EProfile& profile, bool& notFirstToken);

protected:

 // advance one character
 void advance()
 {
 ++currentChar;
 if (currentChar >= lengths[currentSource]) {
 ++currentSource;
 if (currentSource < numSources) {
 loc[currentSource].string = loc[currentSource - 1].string + 1;
 loc[currentSource].line = 1;
 loc[currentSource].column = 0;
 }
 while (currentSource < numSources && lengths[currentSource] == 0) {
 ++currentSource;
 if (currentSource < numSources) {
 loc[currentSource].string = loc[currentSource - 1].string + 1;
 loc[currentSource].line = 1;
 loc[currentSource].column = 0;
 }
 }
 currentChar = 0;
 }
 }

 int numSources; // number of strings in source
 const unsigned char* const *sources; // array of strings; must be converted to positive values on use, to avoid aliasing with -1 as EndOfInput
 const size_t *lengths; // length of each string
 int currentSource;
 size_t currentChar;

 // This is for reporting what string/line an error occurred on, and can be overridden by #line.
 // It remembers the last state of each source string as it is left for the next one, so unget()
 // can restore that state.
 TSourceLoc* loc; // an array

 int stringBias; // the first string that is the user's string number 0
 int finale; // number of internal strings after user's last string

 TSourceLoc logicalSourceLoc;
 bool singleLogical; // treats the strings as a single logical string.
 // locations will be reported from the first string.

 // Set to true once peek() returns EndOfFile, so that we won't roll back
 // once we've reached EndOfFile.
 bool endOfFileReached;
};

} // end namespace glslang

#endif // _GLSLANG_SCAN_INCLUDED_