MESSAGE
| DATE | 2016-04-09 |
| FROM | Ruben Safir
|
| SUBJECT | Re: [Hangout-NYLXS] Antlr visitor Programming - kicking it around
|
On 04/09/2016 09:19 AM, Christopher League wrote:
>
> So I'm only visiting visitAssignID and visitQuantity and
> visitVariables?
>
> Not even visitQuantity, I think. The purpose of CollectVarsVisitor was
> to "traverse a parse tree for the calculator language and just keep
> track of the set of identifiers that are being referenced (assigned or
> retrieved) in the program."
Right. At this point, however, I'm more interested in the mechanics of the
problem than the solution to the example. There is not a visitStmt but
there is a ctx.expr() as a method of an CalcParser.AssignIDContext instance.
Is there a list of potential methods available to me, like gettext()?
Also, examine line
public Void visitPrint(CalcParser.PrintContext ctx)
I have
./CalcParser.java: public void copyFrom(StmtContext ctx) {
and
[ruben-at-manjaro calculator]$ grep StmtContext ./*java
./CalcParser.java: public List stmt() {
./CalcParser.java: return getRuleContexts(StmtContext.class);
./CalcParser.java: public StmtContext stmt(int i) {
./CalcParser.java: return getRuleContext(StmtContext.class,i);
./CalcParser.java: public static class StmtContext extends ParserRuleContext {
./CalcParser.java: public StmtContext(ParserRuleContext parent, int invokingState) {
./CalcParser.java: public StmtContext() { }
./CalcParser.java: public void copyFrom(StmtContext ctx) {
./CalcParser.java: public static class PrintContext extends StmtContext {
./CalcParser.java: public PrintContext(StmtContext ctx) { copyFrom(ctx); }
./CalcParser.java: public static class AssignIDContext extends StmtContext {
./CalcParser.java: public AssignIDContext(StmtContext ctx) { copyFrom(ctx); }
./CalcParser.java: public final StmtContext stmt() throws RecognitionException {
./CalcParser.java: StmtContext _localctx = new StmtContext(_ctx, getState());
./CollectVarsVisitor_bak.java: public Void visitStmt(CalcParser.StmtContext ctx) {
In this case I couldn't grep CalcParse.PrintContext
and
./CalcBaseVisitor.java: -at-Override public T visitPrint(CalcParser.PrintContext ctx) { return visitChildren(ctx); }
[ruben-at-manjaro calculator]$ grep CalcParser.PrintContext ./*java
./CalcBaseListener.java: -at-Override public void enterPrint(CalcParser.PrintContext ctx) { }
./CalcBaseListener.java: -at-Override public void exitPrint(CalcParser.PrintContext ctx) { }
./CalcBaseVisitor.java: -at-Override public T visitPrint(CalcParser.PrintContext ctx) { return visitChildren(ctx); }
./CalcListener.java: void enterPrint(CalcParser.PrintContext ctx);
./CalcListener.java: void exitPrint(CalcParser.PrintContext ctx);
./CalcVisitor.java: T visitPrint(CalcParser.PrintContext ctx);
./CollectVarsVisitor.java: public Void visitPrint(CalcParser.PrintContext ctx) {
Ummm where is CalcParser.PrintContext defined and declared?
hmmm
./CalcParser.java: public static class StmtContext extends ParserRuleContext {
./CalcParser.java: public static class PrintContext extends StmtContext {
Correct?
Oh and remember Unix(GNU) is you f'ing IDE... ;)
need to build ctags..
>
> If we look at the grammar:
> stmt : ID '=' expr #assignID
> | 'print' expr #print
> ;
>
> expr : '-' expr #negative
> | expr ('*' | '/') expr #products_quotents
> | expr ('+'|'-') expr #sums
> | '(' expr ')' #parans
> |NUM #quantity
> |ID #variables
> ;
>
> The only place that a variable is assigned is in #assignID and the only
> place a variable is retrieved is in #variables. So those are the only
> two visit methods we'd need to fulfill the purpose of
> CollectVarsVisitor.
>
> The AssignIDContext and VariablesContext will each have a ctx.ID()
> because ID appears in both of those rules. And because it appears
> exactly once in each, the method returns just a single TerminalNode,
> rather than a list of them. The other contexts (tree nodes) don't have
> any ID, so there is no ctx.ID() method in those.
>
> CL
>
> Ruben Safir [1]ruben-at-mrbrklyn.com writes:
>
> 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 :(' `|'`|'`|'')+ ->skip ;
>
> So I'm only visiting visitAssignID and visitQuantity and
> visitVariables?
>
> Ruben
>
> - So many immigrant groups have swept through our town that
> Brooklyn, like Atlantis, reaches mythological proportions in the
> mind of the world - RI Safir 1998 http://www.mrbrklyn.com
>
> DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
> http://www.nylxs.com - Leadership Development in Free Software
> http://www2.mrbrklyn.com/resources - Unpublished Archive
> http://www.coinhangout.com - coins! http://www.brooklyn-living.com
>
> Being so tracked is for FARM ANIMALS and and extermination camps,
> but incompatible with living as a free human being. -RI Safir 2013
>
> References
>
> 1. mailto:ruben-at-mrbrklyn.com
>
>
>
> _______________________________________________
> hangout mailing list
> hangout-at-nylxs.com
> http://www.nylxs.com/
>
--
So many immigrant groups have swept through our town
that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
http://www.nylxs.com - Leadership Development in Free Software
http://www2.mrbrklyn.com/resources - Unpublished Archive
http://www.coinhangout.com - coins!
http://www.brooklyn-living.com
Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013
_______________________________________________
hangout mailing list
hangout-at-nylxs.com
http://www.nylxs.com/
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