ahillss / tcl-interpreter

First attempt at a TCL interpreter

Minimal TCL Interpreter

A minimal C/C++ embeddable TCL interpreter based off picol. The upvar, uplevel and expr commands have been implemented and eval has been replaced.

Goal is to be very small with no depedencies.

A subset of TCL, though the expr command uses polish notation instead of the infix expressions.

Ragel is used to generate the parsers for eval and expr.

Online example built with emscripten.

Command line:

• REPL : no args
• eval file : filename as arg

Builtin commands:

• upvar : otherVar myVar
• uplevel : body
• expr : expression
• incr : val
• decr : val
• for : start test next body
• while : test body
• if : test body1 else body2

TODO

• "elseif" for "if" command
• implement error stack
• record file, proc and position of errors
• make sure errors propagate through eval and expr calls
• varargs for procs
• backslash escaping spaces, tabs, quotes, brackets etc
• test parsers for certain conditions
• in eval parser, check first word of statement is a command?
• add callback for when undefined commands are called?
• make syntax shortcuts optional (e.g. for $a and ${a})?
• expr: '&&', '||', '?' with short-circuit evaluation
• expr: '~', '!', '%', '&', '^', '|', '**', '<<', '>>', '//', 'eq', 'ne', 'in', 'ni', 'neg', 'abs', 'acos', 'asin', 'atan', 'atan2', 'ceil', 'cos', 'exp', 'floor', 'fmod', 'int', 'log', 'log10', 'max', 'min', 'pow', 'rand', 'round', 'sin', 'sqrt', 'srand', 'tan'