So this means that we could also have a simple hover showing the variable values when debugging. Now clement what is the difference with a plain AST interpreter? On Tue, Apr 17, 2018 at 6:57 PM, Clément Bera <bera.clement@gmail.com> wrote:

Starting from here you can build a full AST interpreter that mutates a context instance that you create by interpreting MessageNode...

On Tue, Apr 17, 2018 at 5:45 PM, Marcus Denker <marcus.denker@inria.fr> wrote:

...

Hi,

This is fun experiment:

Every RBValueNode subclass evaluates to something. So why not implement a #evaluate method?

This is especially fun to do for a specific context, as this means that you could evaluate every RBVariableNode to see the value.

So lets implement a method in RBValueNode:

evaluateWithContext: aContext

| methodNode |

If we want to compile a method for it, we need to wrap it into a return and a method. Like when evaluating in the debugger, we create a #DoItIn: method that will get the context as a parameter to read the values from (temps from the context, ivars from context receiver).

This works like this:

methodNode := RBMethodNode selector: #DoItIn: arguments: { RBVariableNode named: 'ThisContext' } body: (RBReturnNode value: self) asSequenceNode.

to read temps from the context parameter, we use the rewrite method that is used by doits already: methodNode rewriteTempsForContext: aContext.

and now we can execute:

^methodNode generate valueWithReceiver: aContext receiver arguments: {aContext}.

For testing, I put a #haltOnce into Rectangle>>#area and then use the inspector on the context to evaluate a AST node that is a temporary variable. The screenshot shows executing

self method ast assignmentNodes first variable evaluateWithContext: self

and it returns correctly 104:

Of course there are simpler ways to read variables by name from a context (e.g. we added #lookupSymbol: ), but #evaluateWithContext: can be called on other Nodes, too. E.g. just a #evaluate could be nice for creating Blocks programmatically (instead of calling the compiler on a Pretty-Print result like #createBlockFor: in the ParseTreeSearcher).

A version that does not take context and receiver into account is this:

evaluate | methodNode | methodNode := RBMethodNode selector: #DoIt body: (RBReturnNode value: self) asSequenceNode. ^methodNode generate valueWithReceiver: nil arguments: #().

and then you can do things like

blockNode: = RBBlockNode body: (RBLiteralNode value: 5) asSequenceNode

blockNode evaluate

to create blocks.

Marcus

-- Clément Béra https://clementbera.github.io/ https://clementbera.wordpress.com/

On 18 Apr 2018, at 08:11, Marcus Denker <marcus.denker@inria.fr> wrote:

...

On 18 Apr 2018, at 07:41, Stephane Ducasse <stepharo.self@gmail.com> wrote:

So this means that we could also have a simple hover showing the variable values when debugging.

It could be used for that, but then we did have already lookupSymbol: on context (we added that so we can easily use any valid variable in the condition for conditional breakpoints).

Hmm… now that I think about it… I guess evaluateWithContext: could even be used to simplify the code that creates the condition block for conditional breakpoints. This was not even the goal… to be checked. Marcus

2018-04-18 7:41 GMT+02:00 Stephane Ducasse <stepharo.self@gmail.com>:

Now clement what is the difference with a plain AST interpreter?

Together with #evaluate we can also have #debug message. With interpreter approach it would be tricky to implement it with standard debugger.

On Tue, Apr 17, 2018 at 6:57 PM, Clément Bera <bera.clement@gmail.com> wrote:

...

Starting from here you can build a full AST interpreter that mutates a context instance that you create by interpreting MessageNode...

On Tue, Apr 17, 2018 at 5:45 PM, Marcus Denker <marcus.denker@inria.fr> wrote:

...

Hi,

This is fun experiment:

Every RBValueNode subclass evaluates to something. So why not implement a #evaluate method?

This is especially fun to do for a specific context, as this means that you could evaluate every RBVariableNode to see the value.

So lets implement a method in RBValueNode:

evaluateWithContext: aContext

| methodNode |

If we want to compile a method for it, we need to wrap it into a return and a method. Like when evaluating in the debugger, we create a #DoItIn: method that will get the context as a parameter to read the values from (temps from the context, ivars from context receiver).

This works like this:

methodNode := RBMethodNode selector: #DoItIn: arguments: { RBVariableNode named: 'ThisContext' } body: (RBReturnNode value: self) asSequenceNode.

to read temps from the context parameter, we use the rewrite method that is used by doits already: methodNode rewriteTempsForContext: aContext.

and now we can execute:

^methodNode generate valueWithReceiver: aContext receiver arguments: {aContext}.

For testing, I put a #haltOnce into Rectangle>>#area and then use the inspector on the context to evaluate a AST node that is a temporary variable. The screenshot shows executing

self method ast assignmentNodes first variable evaluateWithContext: self

and it returns correctly 104:

Of course there are simpler ways to read variables by name from a context (e.g. we added #lookupSymbol: ), but #evaluateWithContext: can be called on other Nodes, too. E.g. just a #evaluate could be nice for creating Blocks programmatically (instead of calling the compiler on a Pretty-Print result like #createBlockFor: in the ParseTreeSearcher).

A version that does not take context and receiver into account is this:

evaluate | methodNode | methodNode := RBMethodNode selector: #DoIt body: (RBReturnNode value: self) asSequenceNode. ^methodNode generate valueWithReceiver: nil arguments: #().

and then you can do things like

blockNode: = RBBlockNode body: (RBLiteralNode value: 5) asSequenceNode

blockNode evaluate

to create blocks.

Marcus

-- Clément Béra https://clementbera.github.io/ https://clementbera.wordpress.com/