experimental: implement expressions as well as statements

.github/README.md

@@ -40,7 +40,8 @@ that's currently being compiled.
 
 - `Keyword::Simple::define`
 
-    Takes two arguments, the name of a keyword and a coderef. Injects the keyword
+    Takes three arguments, the name of a keyword, a coderef, and a boolean flag if
+    the result of the keyword handler is an expression. Injects the keyword
     in the lexical scope currently being compiled. For every occurrence of the
     keyword, your coderef will be called with one argument: A reference to a scalar
     holding the rest of the source code (following the keyword).
@@ -60,7 +61,7 @@ that's currently being compiled.
 This module depends on the [pluggable keyword](https://metacpan.org/pod/perlapi.html#PL_keyword_plugin)
 API introduced in perl 5.12. Older versions of perl are not supported.
 
-Every new keyword is actually a complete statement by itself. The parsing magic
+Every new keyword is actually a complete statement or an expression by itself. The parsing magic
 only happens afterwards. This means that e.g. the code in the ["SYNOPSIS"](#synopsis)
 actually does this:
 

.travis.yml

@@ -1,7 +1,6 @@
 language: perl
 install: cpanm --quiet --installdeps --with-develop --notest .
 perl:
-    - "5.12"
     - "5.14"
     - "5.16"
     - "5.18"

Makefile_PL_settings.plx

@@ -5,7 +5,7 @@ return {
     NAME   => 'Keyword::Simple',
     AUTHOR => q{Lukas Mai <[email protected]>},
 
-    MIN_PERL_VERSION => '5.12.0',
+    MIN_PERL_VERSION => '5.14.0',
     CONFIGURE_REQUIRES => {},
     BUILD_REQUIRES => {},
     TEST_REQUIRES => {

Simple.xs

@@ -114,9 +114,10 @@ WARNINGS_ENABLE
 
 static int (*next_keyword_plugin)(pTHX_ char *, STRLEN, OP **);
 
-static SV *kw_handler(pTHX_ const char *kw_ptr, STRLEN kw_len) {
+static SV *kw_handler(pTHX_ const char *kw_ptr, STRLEN kw_len, int * is_expr) {
     HV *hints;
     SV **psv, *sv, *sv2;
+    AV *av;
     I32 kw_xlen;
 
 
@@ -152,10 +153,24 @@ static SV *kw_handler(pTHX_ const char *kw_ptr, STRLEN kw_len) {
     }
 
     sv = *psv;
-    if (!(SvROK(sv) && (sv2 = SvRV(sv), SvTYPE(sv2) == SVt_PVCV))) {
-        croak("%s: internal error: $^H{'%s'}{'%.*s'} not a coderef: %"SVf, MY_PKG, HINTK_KEYWORDS, (int)kw_len, kw_ptr, SVfARG(sv));
+    if (!(SvROK(sv) && (av = (AV*)SvRV(sv), SvTYPE((SV*)av) == SVt_PVAV))) {
+        croak("%s: internal error: $^H{'%s'}{'%.*s'} not an arrayref: %"SVf, MY_PKG, HINTK_KEYWORDS, (int)kw_len, kw_ptr, SVfARG(sv));
     }
 
+    if (av_len(av) != 1) {
+        croak("%s: internal error: $^H{'%s'}{'%.*s'} bad arrayref: %"SVf, MY_PKG, HINTK_KEYWORDS, (int)kw_len, kw_ptr, SVfARG(sv));
+    }
+
+    if ( !( psv = av_fetch(av, 0, 0))) {
+        croak("%s: internal error: $^H{'%s'}{'%.*s'} bad item #0: %"SVf, MY_PKG, HINTK_KEYWORDS, (int)kw_len, kw_ptr, SVfARG(sv));
+    }
+    sv2 = *psv;
+
+    if ( !( psv = av_fetch(av, 1, 0))) {
+        croak("%s: internal error: $^H{'%s'}{'%.*s'} bad item #1: %"SVf, MY_PKG, HINTK_KEYWORDS, (int)kw_len, kw_ptr, SVfARG(sv));
+    }
+    *is_expr = SvIV(*psv);
+
     return sv2;
 }
 
@@ -240,11 +255,17 @@ static void total_recall(pTHX_ SV *cb) {
 
 static int my_keyword_plugin(pTHX_ char *keyword_ptr, STRLEN keyword_len, OP **op_ptr) {
     SV *cb;
+    int is_expr;
 
-    if ((cb = kw_handler(aTHX_ keyword_ptr, keyword_len))) {
+    if ((cb = kw_handler(aTHX_ keyword_ptr, keyword_len, &is_expr))) {
         total_recall(aTHX_ cb);
-        *op_ptr = newOP(OP_NULL, 0);
-        return KEYWORD_PLUGIN_STMT;
+	if ( is_expr ) {
+            *op_ptr = parse_fullexpr(0);
+            return KEYWORD_PLUGIN_EXPR;
+	} else {
+            *op_ptr = newOP(OP_NULL, 0);
+            return KEYWORD_PLUGIN_STMT;
+	}
     }
 
     return next_keyword_plugin(aTHX_ keyword_ptr, keyword_len, op_ptr);

lib/Keyword/Simple.pm

@@ -1,7 +1,8 @@
 package Keyword::Simple;
 
-use v5.12.0;
+use v5.14.0;
 use warnings;
+our %kw;
 
 use Carp qw(croak);
 
@@ -12,12 +13,12 @@ BEGIN {
 }
 
 sub define {
-    my ($kw, $sub) = @_;
+    my ($kw, $sub, $expression) = @_;
     $kw =~ /^\p{XIDS}\p{XIDC}*\z/ or croak "'$kw' doesn't look like an identifier";
     ref($sub) eq 'CODE' or croak "'$sub' doesn't look like a coderef";
 
     my %keywords = %{$^H{+HINTK_KEYWORDS} // {}};
-    $keywords{$kw} = $sub;
+    $keywords{$kw} = [ $sub, $expression ? 1 : 0 ];
     $^H{+HINTK_KEYWORDS} = \%keywords;
 }
 
@@ -80,7 +81,8 @@ that's currently being compiled.
 
 =item C<Keyword::Simple::define>
 
-Takes two arguments, the name of a keyword and a coderef. Injects the keyword
+Takes three arguments, the name of a keyword, a coderef, and a boolean flag if
+the result of the keyword handler is an expression. Injects the keyword
 in the lexical scope currently being compiled. For every occurrence of the
 keyword, your coderef will be called with one argument: A reference to a scalar
 holding the rest of the source code (following the keyword).
@@ -100,9 +102,10 @@ method to make the C<no Foo;> syntax work.
 =head1 BUGS AND LIMITATIONS
 
 This module depends on the L<pluggable keyword|perlapi.html/PL_keyword_plugin>
-API introduced in perl 5.12. Older versions of perl are not supported.
+API introduced in perl 5.12. C<parse_> functions were introduced in 5.14.
+Older versions of perl are not supported.
 
-Every new keyword is actually a complete statement by itself. The parsing magic
+Every new keyword is actually a complete statement or an expression by itself. The parsing magic
 only happens afterwards. This means that e.g. the code in the L</SYNOPSIS>
 actually does this:
 

t/basic.t

@@ -2,7 +2,7 @@
 use warnings FATAL => 'all';
 use strict;
 
-use Test::More tests => 2;
+use Test::More tests => 3;
 
 {
     package Foo;
@@ -13,10 +13,14 @@ use Test::More tests => 2;
         Keyword::Simple::define peek => sub {
             substr ${$_[0]}, 0, 0, "ok 1, 'synthetic test';";
         };
+        Keyword::Simple::define poke => sub {
+            substr ${$_[0]}, 0, 0, "ok 2, 'expression' + ' test';";
+        }, 1;
     }
 
     sub unimport {
         Keyword::Simple::undefine 'peek';
+        Keyword::Simple::undefine 'poke';
     }
 
     BEGIN { $INC{"Foo.pm"} = 1; }
@@ -26,3 +30,4 @@ use Foo;
 
 peek
 ok 1, "natural test";
+ok 2, "expression test";