Add Try/Catch support. Not fully formed yet

[ircmaxell]

This adds support for try/catch. Though it is not complete.

Presently, Traverser doesn't fully implement correctly, as it won't traverse the CatchTarget property on the block. This will need to be fixed before merge.

[ircmaxell]

Added colors and changed line types for exception edges to make the image easier to understand.

<?php
try {
    if ($foo) {
        doBar();
    } else {
        doBaz();
    }
} catch (OtherException $e) {
    echo "e";
} catch (Exception $e) {
    echo "a";
} finally {
    echo "b";
}
echo "c";

Renders as

[ircmaxell]

@eric-therond I merged in your changes. Thanks a ton for that so far.

I tried testing with a more aggressive and convoluted flow. I turned of

<?php
try {
    try {
        a:
        echo "a";
        try {
            echo "aa";
        } catch (OtherException $e) {
            echo "ab";
        } finally {
            echo "abc";
        }
    } finally {
        echo "b";
    }
} finally {
    echo "c";
}
echo "d";
goto a;

It's generating what looks on the surface to be the correct text dump:

Block#1
    Stmt_Try
        body: Block#2
        finally: Block#3

Block#2
    Parent: Block#1
        finallyTarget: Block#3
    Stmt_Try
        body: Block#4
        finally: Block#5

Block#3
    Parent: Block#1
    Terminal_Echo
        expr: LITERAL('c')
    Stmt_Jump
        target: Block#6

Block#4
    Parent: Block#2
        finallyTarget: Block#5
    Stmt_Jump
        target: Block#7

Block#5
    Parent: Block#2
        finallyTarget: Block#3
    Terminal_Echo
        expr: LITERAL('b')
    Stmt_Jump
        target: Block#8

Block#6
    Parent: Block#1
    Terminal_Echo
        expr: LITERAL('d')
    Stmt_Jump
        target: Block#7

Block#7
    Parent: Block#4
    Parent: Block#6
        finallyTarget: Block#5
    Terminal_Echo
        expr: LITERAL('a')
    Stmt_Try
        catchTypes[0]: LITERAL('OtherException')
        catchVars[0]: Var#1<$e>
        body: Block#9
        catch[0]: Block#10
        finally: Block#11

Block#8
    Parent: Block#2
        finallyTarget: Block#3
    Stmt_Jump
        target: Block#3

Block#9
    Parent: Block#7
        catchTarget<LITERAL('OtherException')>(Var#1<$e>): Block#10
        finallyTarget: Block#11
    Terminal_Echo
        expr: LITERAL('aa')
    Stmt_Jump
        target: Block#11

Block#10
    Parent: Block#7
        finallyTarget: Block#11
    Terminal_Echo
        expr: LITERAL('ab')
    Stmt_Jump
        target: Block#11

Block#11
    Parent: Block#7
        finallyTarget: Block#5
    Terminal_Echo
        expr: LITERAL('abc')
    Stmt_Jump
        target: Block#12

Block#12
    Parent: Block#7
        finallyTarget: Block#5
    Stmt_Jump
        target: Block#5

And the CFG diagram generated looks solid too (though it is non-obvious since jumps aren't labeled)

And with the optimzier turned on (Traverser enabled):

So overall this looks good to me so far. Anything else missing at this point?

[eric-therond]

Thank you for all your advice and for moving this project forward.

Also, Thinking about it a bit more, I think each of the catch blocks and finally blocks should have every block which has them as a catchtarget as a parent so that controlflow is modeled correctly (phi nodes, etc).

From what you suggested here on another thread, I think this is still missing, I can try to add it later.

[eric-therond]

I created a pull request on parents, I would say it is actually enough if:

• the only parents of a finally block are catchs blocks and try body block
• and the only parent of catch blocks is the try body block
• the only parent of next block is the try body block

?

[eric-therond]

Forget my previous message.

I now understand that in the event of an exception that can occur anywhere, it may be desirable to add an edge from any block in the try body to the catch/finally blocks?

I've fixed the PR in this direction.

[ircmaxell]

Anything else missing here? Is this ready to merge?

[eric-therond]

Yes it looks ok for me.

[ircmaxell]

Really well done here, thanks for the back and forth, the polish, and driving it to completion!

[eric-therond]

Thank to you! It's a very interesting project to work on.
A quick request: is it possible to release a new version, 0.8.0 of php-cfg?

[ircmaxell]

Done: https://github.com/ircmaxell/php-cfg/releases/tag/v0.8.0