Turtle Graphics - A Simple Parser

embed[0]: This embedded VRML world includes Tommy the turtle. He is sent commands generated by the tree walkover. These are results of the interpretation process.

Problems

Copy to local file space the files logo.htm Stream.js Lexer.js Parser.js
Add the key words bk, dv and rl (for back, dive and roll) to the language. That should allow you to execture the logo program sp1.txt.
Add the key word repeat to the language to permit and ot the following logo programs: a.txt, sp2.txt, b.txt and c.txt

source: This text is the input to the LEX/PARSE/INTERPRET system.	lex_out: This text box shows the output of the lexical analyser. Each lexical token has three components: TOKEN_TYPE, VALUE, LINE_NUMBER
fd 100 #Go forward 100 lt 90 fd 100 lt 90 #Note comments are removed fd 100 #by the lexical analyser lt 90 fd 100 lt 90
parse_out: This box shows the parse tree as returned by Parse_L the top level parse function.