diff options
Diffstat (limited to 'src/front/parser.py')
| -rw-r--r-- | src/front/parser.py | 59 |
1 files changed, 29 insertions, 30 deletions
diff --git a/src/front/parser.py b/src/front/parser.py index 610a5bb..511e929 100644 --- a/src/front/parser.py +++ b/src/front/parser.py @@ -1,37 +1,41 @@ # -*- coding: utf-8 -*- from ast import * -from lexer import * -from token import * +from token import Tag +from scope import Scope + +class ParseError(Exception): + pass class Parser: - def __init__(self, lex): - self.lexer = lex - self.token = lex.scan() - self.count = 1 #debug - return + def __init__(self, lexer): + self.lexer = lexer + self.scope = Scope() + self.move() def parse(self): return self.program() def move(self): - print self.count, self.token #debug - self.count += 1 #debug self.token = self.lexer.scan() - return + #print "move(): %s" % self.token def error(self, msg): - raise Exception(msg) + raise ParseError(msg) - def match(self, tag): + def _match(self, tag): if self.token == None: self.error("Unexpected end of file.") - if self.token.tag != tag: self.error("match: expected %s got %s\n" %(tag, self.token.tag)) val = self.token.value self.move() return val + def match(self, tag, *tags): + for t in (tag,) + tags: + res = self._match(t) + return res + # boolean = join { "||" join }. def boolean(self): res = self.join() @@ -94,8 +98,7 @@ class Parser: # function_call = "call" ident "[" [ expression_list ] "]". def function_call(self): - self.match(Tag.CALL) - name = self.match(Tag.IDENT) + name = self.match(Tag.CALL, Tag.IDENT) self.match(Tag.LBRAK) args = [] if self.token.tag == Tag.RBRAK else self.expression_list() self.match(Tag.RBRAK) @@ -126,23 +129,20 @@ class Parser: # statement_list = statement { statement }. def statement_list(self): - stat = [self.statement()] - while self.token.tag not in [Tag.END, Tag.ELSE]: - stat.append(self.statement()) - return stat + if self.token.tag in [Tag.END, Tag.ELSE]: + return None + return Sequence(self.statement(), self.statement_list(), self.lexer.line) # function = "fun" ident "[" [ ident_list ] "]" nl statement_list "end" nl. def function(self): line = self.lexer.line - self.match(Tag.FUN) - name = self.match(Tag.IDENT) + name = self.match(Tag.FUN, Tag.IDENT) self.match(Tag.LBRAK) args = [] if self.token.tag == Tag.RBRAK else self.ident_list() - self.match(Tag.RBRAK) - self.match(Tag.NEWLINE) + self.match(Tag.RBRAK, Tag.NEWLINE) + self.scope.new(name, args) block = self.statement_list() - self.match(Tag.END) - self.match(Tag.NEWLINE) + self.match(Tag.END, Tag.NEWLINE) return Function(name, args, block, line) # statement = [ if_statement | while_statement | assign_statement | return_statement | function_call ]. @@ -161,13 +161,12 @@ class Parser: condition = self.boolean() self.match(Tag.NEWLINE) true_case = self.statement_list() - else_case = [] + else_case = None if self.token.tag == Tag.ELSE: self.move() self.match(Tag.NEWLINE) else_case = self.statement_list() - self.match(Tag.END) - self.match(Tag.NEWLINE) + self.match(Tag.END, Tag.NEWLINE) return IfStatement(condition, true_case, else_case, line) # while_statement = "while" boolean nl statement_list "end" nl. @@ -177,8 +176,7 @@ class Parser: condition = self.boolean() self.match(Tag.NEWLINE) body = self.statement_list() - self.match(Tag.END) - self.match(Tag.NEWLINE) + self.match(Tag.END, Tag.NEWLINE) return WhileStatement(condition, body, line) # return_statement = "@" boolean nl. @@ -196,6 +194,7 @@ class Parser: self.match(Tag.ASSIGNMENT) exp = self.boolean() self.match(Tag.NEWLINE) + self.scope.add(name) return AssignStatement(name, exp, line) # program = function_list. |