MESSAGE
| DATE | 2016-04-08 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Hangout-NYLXS] Antlr visitor Programming - kicking it around
|
So kicking this around, forget that this HW is now a month old...
I did this which fails, and I know why...I think
Note that it fails on contex objects that have no ID()
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.tree.ParseTree;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;
import java.util.HashSet;
public class CollectVarsVisitor extends CalcBaseVisitor {
HashSet vars = new HashSet();
//STMT
-at-Override
public Void visitAssignID(CalcParser.AssignIDContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println(id.getText());
vars.add(id.getText());
}
return super.visitAssignID(ctx);
}
-at-Override
public Void visitPrint(CalcParser.PrintContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println(id.getText());
vars.add(id.getText());
}
return super.visitPrint(ctx);
}
//EXPR
-at-Override
public Void visitNegative(CalcParser.NegativeContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitNegative(ctx);
}
-at-Override
public Void visitProducts_quotents(CalcParser.Products_quotentsContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitProducts_quotents(ctx);
}
-at-Override
public Void visitSums(CalcParser.SumsContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitSums(ctx);
}
-at-Override
public Void visitParans(CalcParser.ParansContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitParans(ctx);
}
-at-Override
public Void visitQuantity(CalcParser.QuantityContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitQuantity(ctx);
}
-at-Override
public Void visitVariables(CalcParser.VariablesContext ctx) {
TerminalNode id = ctx.ID();
if(id != null) {
System.out.println("expresion: " + id.getText());
vars.add(id.getText());
}
return super.visitVariables(ctx);
}
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[ruben-at-manjaro calculator]$ javac Main.java
./CollectVarsVisitor.java:25: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type PrintContext
./CollectVarsVisitor.java:37: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type NegativeContext
./CollectVarsVisitor.java:48: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type Products_quotentsContext
./CollectVarsVisitor.java:58: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type SumsContext
./CollectVarsVisitor.java:68: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type ParansContext
./CollectVarsVisitor.java:78: error: cannot find symbol
TerminalNode id = ctx.ID();
^
symbol: method ID()
location: variable ctx of type QuantityContext
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
6 errors
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cat Calc.g4
grammar Calc;
prog : (stmt ';')*
;
stmt : ID '=' expr #assignID
| 'print' expr #print
;
expr : '-' expr #negative
| expr ('*' | '/') expr #products_quotents
| expr ('+'|'-') expr #sums
| '(' expr ')' #parans
|NUM #quantity
|ID #variables
;
NUM : [0-9]+ ('.' [0-9]+)?
;
ID :[a-zA-Z]+
;
WS :(' '|'\n'|'\t'|'\r')+ ->skip
;
So I'm only visiting visitAssignID and visitQuantity and visitVariables?
Ruben
--
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that Brooklyn, like Atlantis, reaches mythological
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Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013
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