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From: =?utf-8?Q?Jesper_Steen_M=C3=B8ller?= <jesper@selskabet.org>
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Subject: Re: How to find out the names of variables used in a groovy
 expression
Date: Sun, 26 Nov 2017 12:32:32 +0100
References: <1511692357583-0.post@n5.nabble.com>
To: dev@groovy.apache.org
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Message-Id: <3230CADE-4E9E-4BDA-B361-F2EC43226765@selskabet.org>
archived-at: Sun, 26 Nov 2017 11:32:41 -0000


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HI Greg,

Note: This list is primarily for developers and maintainers of the =
Groovy project, not for how to use Groovy. You could try =
users@groovy.apache.org instead. As for your question, which is =
admittedly borderline:
1) At compile time (i.e. in a macro or AST transformer), this should be =
doable, but it's not a slam-dunk oneliner (you need to drill down into =
each GString-expression in the abstract syntax tree and find out how =
each expression is constructed, and which variable/field names are in =
use)
2) At runtime, string interpolation has already expanded into a =
construction of a GString by the compiler, and by that time, the =
expressions are no logner recognizable (generally speaking).

I can't quite guess what you're trying to accomplish, but perhaps you =
should consider a templating engine instead, for the ability to parse =
and work with GString-like templates. Have a look at =
http://docs.groovy-lang.org/latest/html/documentation/template-engines.htm=
l =
<http://docs.groovy-lang.org/latest/html/documentation/template-engines.ht=
ml>

-Jesper

> On 26 Nov 2017, at 11.32, bayareagreg <bayareagreg@gmail.com> wrote:
>=20
> Hello,
>=20
> I need to programmatically find out the names of variables used in a
> "simple" groovy expression that reads a value from one or more =
variables.
> One can assume the expression is read-only, that is no modifications =
of any
> state will be used. E.g. in an expression like this
>=20
> "${foo}", it should return "foo"
> also same in "${foo.bar.zot}"
>=20
> is what I am asking possible? If yes please point me in the direction =
of
> which API to use for this.
> Thank you in advance
>=20
>=20
>=20
>=20
> --
> Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html


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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dus-ascii"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
class=3D""><div class=3D"">HI Greg,</div><div class=3D""><br =
class=3D""></div><div class=3D"">Note: This list is primarily for =
developers and maintainers of the Groovy project, not for how to use =
Groovy. You could try <a href=3D"mailto:users@groovy.apache.org" =
class=3D"">users@groovy.apache.org</a> instead. As for your question, =
which is admittedly borderline:</div><div class=3D"">1) At compile time =
(i.e. in a macro or AST transformer), this should be doable, but it's =
not a slam-dunk oneliner (you need to drill down into each =
GString-expression in the abstract syntax tree and find out how each =
expression is constructed, and which variable/field names are in =
use)</div><div class=3D"">2) At runtime, string interpolation has =
already expanded into a construction of a GString by the compiler, and =
by that time, the expressions are no logner recognizable (generally =
speaking).</div><div class=3D""><br class=3D""></div><div class=3D"">I =
can't quite guess what you're trying to accomplish, but perhaps you =
should consider a templating engine instead, for the ability to parse =
and work with GString-like templates. Have a look at&nbsp;<a =
href=3D"http://docs.groovy-lang.org/latest/html/documentation/template-eng=
ines.html" =
class=3D"">http://docs.groovy-lang.org/latest/html/documentation/template-=
engines.html</a><div class=3D""><br class=3D""></div><div =
class=3D"">-Jesper</div><div class=3D""><br class=3D""><div><blockquote =
type=3D"cite" class=3D""><div class=3D"">On 26 Nov 2017, at 11.32, =
bayareagreg &lt;<a href=3D"mailto:bayareagreg@gmail.com" =
class=3D"">bayareagreg@gmail.com</a>&gt; wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div =
class=3D"">Hello,<br class=3D""><br class=3D"">I need to =
programmatically find out the names of variables used in a<br =
class=3D"">"simple" groovy expression that reads a value from one or =
more variables.<br class=3D"">One can assume the expression is =
read-only, that is no modifications of any<br class=3D"">state will be =
used. E.g. in an expression like this<br class=3D""><br =
class=3D"">"${foo}", it should return "foo"<br class=3D"">also same in =
"${foo.bar.zot}"<br class=3D""><br class=3D"">is what I am asking =
possible? If yes please point me in the direction of<br class=3D"">which =
API to use for this.<br class=3D"">Thank you in advance<br class=3D""><br =
class=3D""><br class=3D""><br class=3D""><br class=3D"">--<br =
class=3D"">Sent from: <a =
href=3D"http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html" =
class=3D"">http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html</a><=
br class=3D""></div></div></blockquote></div><br =
class=3D""></div></div></body></html>=

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