"""

Parse Linogram source code as defined in HOP.

(The full Perl Linogram has more features.)

The grammar is a direct port of the one in Higher Order Perl,

which is copyright by Mark Jason Dominus.

"""

from parson import Grammar, Unparsable

import interpreter

grammar = Grammar(r""" (definition | declaration)* ('__END__' | :end).

definition: defheader '{' [declaration* :hug] '}' :Definition.

defheader: "define" ID ("extends" ID | :None).

declaration: ID declarators ';' :VarDecl

| constraint_section

| draw_section.

declarators: declarator++',' :hug.

declarator: ID [('(' param_spec++',' ')')? :hug] :Declarator.

param_spec: ID '=' expression :hug.

constraint_section: "constraints" '{' constraint* '}' :hug :Constraints.

constraint: expression '=' expression ';' :hug.

draw_section: "draw" '{' drawable* '}' :hug :Draw.

drawable: name ';' :DrawName

| '&' ID ';' :DrawFunction.

expression: term ('+' term :Add

|'-' term :Sub)*.

term: atom ('*' atom :Mul

|'/' atom :Div)*.

atom: name

| tuple

| NUMBER :Number

| '-' expression :Negate

| '(' expression ')'.

name: ID :Name ('.' ID :Dot)*.

tuple: '(' expression (',' expression)+ ')' :hug :Tuple.

# Lexical grammar

ID: /([a-zA-Z_]\w*)/. # XXX need to rule out keywords?

NUMBER ~: { mantissa /[eE]\d+/? } FNORD :float.

mantissa ~: /\d+/ ('.' /\d*/)?

| '.' /\d+/.

FNORD ~: /\s*/.

""")

parse = grammar.bind(interpreter)