def parseSwitchStmt(self, exp):
## @ <ID/EXPR> SWITCH @( expr ) CASE {stmtlist} @( expr ) CASE {stmtlist} OTHERWISE {stmtlist} END
## implement as an if-elseif-else statement
self.dbg_msg("parsing SWITCH statement")
sw_tok = self.dequeue()
[l, c] = sw_tok.get_line_col()
self.inside_if = True
lhs = exp[0]
# enter this if-statement always
ifstmt = IfStmt(Number(1), None, None, l, c, self.debug)
self.if_stack.append(ifstmt)
self.dbg_msg("parsing SWITCH-body") #self.dbg_msg
ptok = self.peek()
equality_token = EzhilLexeme("=", EzhilToken.EQUALITY)
while (ptok.kind == EzhilToken.ATRATEOF
or ptok.kind == EzhilToken.OTHERWISE):
self.inside_if = True
[l, c] = ptok.get_line_col()
if (ptok.kind == EzhilToken.ATRATEOF):
# parse elseif branch
self.dbg_msg("parsing CASE")
self.match(EzhilToken.ATRATEOF)
exp = self.valuelist()
self.dbg_msg("parsing CASE EXPR")
self.match(EzhilToken.CASE)
next_stmt = self.stmtlist()
expr = Expr(lhs, equality_token, exp[0], l, c, self.debug)
self.dbg_msg("building an Expr " + str(expr))
if not ifstmt.body:
ifstmt.expr = expr
ifstmt.body = next_stmt
else:
case_stmt = IfStmt(expr, next_stmt, None, l, c, self.debug)
ifstmt.append_stmt(case_stmt)
elif (ptok.kind == EzhilToken.OTHERWISE):
#parse else branch
self.dbg_msg("parsing OTHERWISE: ")
self.match(EzhilToken.OTHERWISE)
self.dbg_msg("parsing OTHERWISE-Body")
self.inside_if = False
body = self.stmtlist()
else_stmt = ElseStmt(body, l, c, self.debug)
if not ifstmt.body:
ifstmt.body = else_stmt
else:
ifstmt.append_stmt(else_stmt)
break
else:
self.inside_if = False
raise ParseError(
"SWITCH-CASE-OTHERWISE statement syntax is messed up")
ptok = self.peek()
self.dbg_msg("parsing SWITCH-CASE next bits " + str(ptok))
self.match(EzhilToken.END)
self.inside_if = False
self.dbg_msg("parsing -SWITCH-CASE- complete")
return ifstmt
def parseIfStmt(self, exp):
## @ <expression> if { stmtlist } @<expr> ELSEIF {stmtlist} ELSE <stmtlist> END
self.dbg_msg("parsing IF statement")
if_tok = self.dequeue()
[l, c] = if_tok.get_line_col()
self.inside_if = True
ifstmt = IfStmt(exp[0], None, None, l, c, self.debug)
self.if_stack.append(ifstmt)
self.dbg_msg("parsing IF-body")
body = self.stmtlist()
prev_body = body
ifstmt.set_body(body)
ptok = self.peek()
while (ptok.kind == EzhilToken.ATRATEOF
or ptok.kind == EzhilToken.ELSE):
self.inside_if = True
[l, c] = ptok.get_line_col()
if (ptok.kind == EzhilToken.ATRATEOF):
# parse elseif branch
self.dbg_msg("parsing ELSE-IF")
self.match(EzhilToken.ATRATEOF)
exp = self.valuelist()
self.dbg_msg("parsing ELSE-IF EXPR")
tok = self.peek()
if (tok.kind != EzhilToken.ELSEIF):
# maybe another IF statement, SWITCH-CASE or a WHILE loop, DO-WHILE loop etc.
next_stmt = self.stmtlist(exp) #pass in the expression
prev_body.append(next_stmt)
# append to previously scanned body.
else:
self.dbg_msg("parsing ELSE-IF-body")
self.match(EzhilToken.ELSEIF)
body = self.stmtlist()
prev_body = body
next_stmt = IfStmt(exp[0], body, None, l, c, self.debug)
ifstmt.append_stmt(next_stmt)
elif (ptok.kind == EzhilToken.ELSE):
#parse else branch
self.dbg_msg("parsing stmt else: ")
self.match(EzhilToken.ELSE)
self.dbg_msg("parsing ELSE-Body")
self.inside_if = False
body = self.stmtlist()
prev_body = body
else_stmt = ElseStmt(body, l, c, self.debug)
ifstmt.append_stmt(else_stmt)
break
else:
self.inside_if = False
raise ParseException(
"If-Else-If statement syntax is messed up")
ptok = self.peek()
self.dbg_msg("parsing -IF next bits " + str(ptok))
self.match(EzhilToken.END)
self.inside_if = False
self.dbg_msg("parsing -IF-complete")
return ifstmt
def stmt(self):
""" try an assign, print, return, if or eval statement """
self.dbg_msg(" STMT ")
ptok = self.peek()
self.dbg_msg("stmt: peeking at " + str(ptok))
if (ptok.kind == Token.RETURN):
## return <expression>
ret_tok = self.dequeue()
[l, c] = ret_tok.get_line_col()
rstmt = ReturnStmt(self.expr(), l, c, self.debug)
self.dbg_msg("return statement parsed")
return rstmt
elif (ptok.kind == Token.PRINT):
## print <expression>
print_tok = self.dequeue()
[l, c] = print_tok.get_line_col()
return PrintStmt(self.exprlist(), l, c, self.debug)
elif (ptok.kind == Token.IF):
## if <expression> stmtlist end
if_tok = self.dequeue()
[l, c] = if_tok.get_line_col()
exp = self.expr()
ifstmt = IfStmt(exp, None, None, l, c, self.debug)
self.if_stack.append(ifstmt)
body = self.stmtlist()
ifstmt.set_body(body)
ptok = self.peek()
if (ptok.kind in [Token.ELSEIF, Token.ELSE]):
self.inside_if = True
next_stmt = self.stmtlist()
self.inside_if = False
ifstmt.append_stmt(next_stmt)
self.match(Token.END)
return ifstmt
elif (ptok.kind == Token.ELSEIF):
## elseif <expression> stmtlist
elseif_tok = self.dequeue()
[l, c] = elseif_tok.get_line_col()
self.check_if_stack()
exp = self.expr()
elseif_stmt = IfStmt(exp, None, None, l, c, self.debug)
ifstmt = self.if_stack[-1]
ifstmt.append_stmt(elseif_stmt)
self.if_stack.pop()
self.if_stack.append(elseif_stmt)
body = self.stmtlist()
elseif_stmt.set_body(body)
return elseif_stmt
elif (ptok.kind == Token.ELSE):
## else stmtlist
self.check_if_stack()
ifstmt = self.if_stack.pop()
self.dbg_msg("stmt-else: ")
else_tok = self.dequeue()
[l, c] = else_tok.get_line_col()
body = self.stmtlist()
else_stmt = ElseStmt(body, l, c, self.debug)
ifstmt.append_stmt(else_stmt)
return else_stmt
elif (ptok.kind == Token.FOR):
## Fixme : empty for loops not allowed.
""" For ( exp1 ; exp2 ; exp3 ) stmtlist end"""
self.loop_stack.append(True)
self.dbg_msg("for-statement")
for_tok = self.dequeue()
self.match(Token.LPAREN)
lhs = self.expr()
init = lhs
ptok = self.peek()
if (ptok.kind in Token.ASSIGNOP):
assign_tok = self.dequeue()
[l, c] = assign_tok.get_line_col()
rhs = self.expr()
init = AssignStmt(lhs, assign_tok, rhs, l, c, self.debug)
self.match(Token.COMMA)
cond = self.expr()
self.match(Token.COMMA)
lhs = self.expr()
update = lhs
ptok = self.peek()
if (ptok.kind in Token.ASSIGNOP):
assign_tok = self.dequeue()
[l, c] = assign_tok.get_line_col()
rhs = self.expr()
update = AssignStmt(lhs, assign_tok, rhs, l, c, self.debug)
self.match(Token.RPAREN)
body = self.stmtlist()
self.match(Token.END)
[l, c] = for_tok.get_line_col()
forstmt = ForStmt(init, cond, update, body, l, c, self.debug)
self.loop_stack.pop()
return forstmt
elif (ptok.kind == Token.WHILE):
## while ( expr ) body end
self.loop_stack.append(True)
self.dbg_msg("while-statement")
while_tok = self.dequeue()
[l, c] = while_tok.get_line_col()
wexpr = self.expr()
body = self.stmtlist()
self.match(Token.END)
whilestmt = WhileStmt(wexpr, body, l, c, self.debug)
self.loop_stack.pop()
return whilestmt
elif (ptok.kind == Token.BREAK):
## break, must be in loop-environment
self.dbg_msg("break-statement")
break_tok = self.dequeue()
[l, c] = break_tok.get_line_col()
self.check_loop_stack()
##raises a parse error
brkstmt = BreakStmt(l, c, self.debug)
return brkstmt
elif (ptok.kind == Token.CONTINUE):
## continue, must be in loop-environment
self.dbg_msg("continue-statement")
cont_tok = self.dequeue()
[l, c] = cont_tok.get_line_col()
self.check_loop_stack()
##raises a parse error
cntstmt = ContinueStmt(l, c, self.debug)
return cntstmt
else:
## lval := rval
ptok = self.peek()
[l, c] = ptok.get_line_col()
lhs = self.expr()
self.dbg_msg("parsing expr: " + str(lhs))
ptok = self.peek()
if (ptok.kind in Token.ASSIGNOP):
assign_tok = self.dequeue()
rhs = self.expr()
[l, c] = assign_tok.get_line_col()
return AssignStmt(lhs, assign_tok, rhs, l, c, self.debug)
return EvalStmt(lhs, l, c, self.debug)
raise ParseException("parsing Statement, unkown operators" + str(ptok))