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@lexer::members { class SaveStruct { SaveStruct(CharStream input){ this.input = input; this.marker = input.mark(); } public CharStream input; public int marker; } Stack<SaveStruct> includes = new Stack<SaveStruct>(); // We should override this method for handling EOF of included file public Token nextToken(){ Token token = super.nextToken(); if(token.getType() == Token.EOF_TOKEN && !includes.empty()){ // We've got EOF and have non empty stack. SaveStruct ss = includes.pop(); setCharStream(ss.input); input.rewind(ss.marker); //this should be used instead of super [like below] to handle exits from nested includes //it matters, when the 'include' token is the last in previous stream (using super, lexer 'crashes' returning EOF token) token = this.nextToken(); } // Skip first token after switching on another input. // You need to use this rather than super as there may be nested include files if(((CommonToken)token).getStartIndex() < 0) token = this.nextToken(); return token; } } // and lexer rule INCLUDE : 'include' (WS)? f=STRING { String name = f.getText(); name = name.substring(1,name.length()-1); try { // save current lexer's state SaveStruct ss = new SaveStruct(input); includes.push(ss); // switch on new input stream setCharStream(new ANTLRFileStream(name)); reset(); } catch(Exception fnf) { throw new Error("Cannot open file " + name); } } ; |
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