Language::AttributeGrammars.
Repase la sección
9.5
(Usando Language::AttributeGrammars con Parse::Eyapp).
Es conveniente que las acciones sean aisladas en subrutinas para evitar que Language::AttributeGrammars se confunda. Sigue un ejemplo de como podria hacerse:
pl@nereida:~/doc/casiano/PLBOOK/PLBOOK/code/Simple-AttributeGrammar/lib$ \
sed -ne '585,631p' Trans_Scheme.eyp
my $attgram = new Language::AttributeGrammar <<'EOG';
# Tipos Basicos
INUM: $/.t = { Trans_Scheme::inum }
CHARCONSTANT: $/.t = { Trans_Scheme::char_constant }
# Variables escalares y arrays
VAR: $/.t = { Trans_Scheme::var($/) }
# Expresiones binarias
PLUS: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
MINUS: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
TIMES: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
DIV: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
MOD: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
GT: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
GE: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
LE: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
EQ: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
NE: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
LT: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
AND: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
OR: $/.t = { Trans_Scheme::bin($<0>.t, $<1>.t, $/) }
# Sentencias de control
IF: $/.t = { Trans_Scheme::condition($<0>.t, $/, $<1>.t) }
IFELSE: $/.t = { Trans_Scheme::condition($<0>.t, $/, $<1>.t, $<2>.t) }
WHILE: $/.t = { Trans_Scheme::condition($<0>.t, $/, $<1>.t) }
# Asignaciones
ASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
PLUSASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
MINUSASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
TIMESASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
DIVASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
MODASSIGN: $/.t = { Trans_Scheme::assign($<0>.t, $<1>.t, $/) }
# Llamadas a funciones
FUNCTIONCALL: $/.t = { Trans_Scheme::functioncall($/) }
# Return
RETURN: $/.t = { Trans_Scheme::return($<0>.t, $/) }
# Otros nodos
LABEL: $/.t = { Trans_Scheme::void }
GOTO: $/.t = { Trans_Scheme::void }
STATEMENTS: $/.t = { Trans_Scheme::void }
BLOCK: $/.t = { Trans_Scheme::void }
BREAK: $/.t = { Trans_Scheme::void }
CONTINUE: $/.t = { Trans_Scheme::void }
FUNCTION: $/.t = { Trans_Scheme::void }
PROGRAM: $/.t = { Trans_Scheme::void }
EOG
Las funciones de soporte son similares a las que hemos usado en Trans.trg:
pl@nereida:~/doc/casiano/PLBOOK/PLBOOK/code/Simple-AttributeGrammar/lib$ sed -ne '716,721p' Trans_Scheme.eyp
sub return {
my ($t, $fathernode) = @_;
my $child = $fathernode->child(0);
return $t if ($types->{$fathernode->{returntype}} == $t);
type_error("Type error in return statement", $fathernode->line);
}