Make template live reload account for dependencies

Fixes #57.

lib/Cro/WebApp/Template/AST.pm6

@@ -13,6 +13,8 @@ my role ContainerNode does Node {
 }
 
 my class Template does ContainerNode is export {
+    has @.used-files;
+
     method compile() {
         my $*IN-SUB = False;
         my $children-compiled = @!children.map(*.compile).join(", ");
@@ -25,7 +27,7 @@ my class Template does ContainerNode is export {
         }
         my %*TEMPLATE-EXPORTS = :sub{}, :macro{};
         my $renderer = EVAL 'sub ($_) { join "", (' ~ $children-compiled ~ ') }';
-        return { :$renderer, exports => %*TEMPLATE-EXPORTS };
+        return Map.new((:$renderer, exports => %*TEMPLATE-EXPORTS, :@!used-files));
     }
 }
 

lib/Cro/WebApp/Template/ASTBuilder.pm6

@@ -46,7 +46,9 @@ class Cro::WebApp::Template::ASTBuilder {
                     exported-subs => $loaded-prelude.exports<sub>.keys,
                     exported-macros => $loaded-prelude.exports<macro>.keys;
         }
-        make Template.new(children => [|@prelude, |flatten-literals($<sequence-element>.map(*.ast))]);
+        make Template.new:
+                children => [|@prelude, |flatten-literals($<sequence-element>.map(*.ast))],
+                used-files => @*USED-FILES;
     }
 
     method sequence-element:sym<sigil-tag>($/) {
@@ -189,6 +191,7 @@ class Cro::WebApp::Template::ASTBuilder {
         with $<file> {
             my $template-name = .ast;
             my $used = await $*TEMPLATE-REPOSITORY.resolve($template-name, @*TEMPLATE-LOCATIONS);
+            @*USED-FILES.push($used);
             make UseFile.new: :path($used.path),
                     exported-subs => $used.exports<sub>.keys,
                     exported-macros => $used.exports<macro>.keys;

lib/Cro/WebApp/Template/Parser.pm6

@@ -21,6 +21,7 @@ grammar Cro::WebApp::Template::Parser {
     token TOP {
         :my $*IN-ATTRIBUTE = False;
         :my $*IN-MACRO = False;
+        :my @*USED-FILES;
         <sequence-element>*
         [ $ || <.panic: 'confused'> ]
     }

lib/Cro/WebApp/Template/Repository.pm6

@@ -20,6 +20,9 @@ class Cro::WebApp::Template::Compiled is implementation-detail {
     #| The source file for the template, if available.
     has IO::Path $.path;
 
+    #| Files that are used by this template.
+    has Cro::WebApp::Template::Compiled @.used-files;
+
     # Implementation details.
     has &.renderer;
     has %.exports;
@@ -77,7 +80,7 @@ monitor Cro::WebApp::Template::Repository::FileSystem does Cro::WebApp::Template
         }
         for @!global-search-paths {
             my $path = .add($template-name);
-            return self.resolve-absolute($path, :@locations) if $path.f;
+            return self.resolve-absolute($path.absolute.IO, :@locations) if $path.f;
         }
         die X::Cro::WebApp::Template::NotFound.new(:$template-name);
     }
@@ -110,17 +113,44 @@ monitor Cro::WebApp::Template::Repository::FileSystem does Cro::WebApp::Template
 #| disk changes. Ideal for development time.
 monitor Cro::WebApp::Template::Repository::FileSystem::Reloading is Cro::WebApp::Template::Repository::FileSystem {
     has %!abs-path-to-mtime;
+    has %!dependencies;
 
     #| Loads a template from an absolute path. If the file at that path didn't
-    #| change since the last template compilation, then the cached compilation of
-    #| the template is returned. Otherwise, it is recompiled.
+    #| change since the last template compilation, nor any of the templates
+    #| that it depends on, then the cached compilation of the template is
+    #| returned. Otherwise, it is recompiled.
     method resolve-absolute(IO() $abs-path, :@locations --> Promise) {
-        my $modified = $abs-path.IO.modified;
+        my $modified = $abs-path.modified;
         if (%!abs-path-to-mtime{$abs-path} // 0) != $modified {
             self.refresh($abs-path)
         }
+        elsif %!dependencies{$abs-path} -> @deps {
+            for @deps -> $dep-path {
+                my $dep-modified = $dep-path.modified;
+                if (%!abs-path-to-mtime{$dep-path} // 0) != $dep-modified {
+                    self.refresh($abs-path);
+                    last;
+                }
+            }
+        }
         %!abs-path-to-mtime{$abs-path} = $modified;
-        callsame
+        my Promise $compiled-promise = callsame;
+        $compiled-promise.then: {
+            if $compiled-promise.status == Kept {
+                self.update-dependencies($compiled-promise.result);
+            }
+        }
+        $compiled-promise
+    }
+
+    method update-dependencies($compiled) {
+        sub collect-deps(Cro::WebApp::Template::Compiled $compiled) {
+            for $compiled.used-files -> $used {
+                take .absolute.IO with $used.path;
+                collect-deps($used);
+            }
+        }
+        %!dependencies{$compiled.path.absolute} = eager gather collect-deps($compiled);
     }
 }
 

t/template-reload.t

@@ -1,12 +1,28 @@
 BEGIN %*ENV<CRO_DEV> = True;
 use Test;
 use Cro::WebApp::Template;
-plan 2;
+plan 4;
 
 my $test-file = $*PROGRAM.parent.add('test-data').add('reload.crotmp');
 END try unlink $test-file;
 $test-file.spurt: 'Hello <.name>.';
-is render-template($test-file, {name => "World"}), 'Hello World.';
+is render-template($test-file, {name => "World"}), 'Hello World.',
+    'Correct rendering before change';
 
 $test-file.spurt: 'Goodbye <.name>!';
-is render-template($test-file, {name => "dlroW"}), 'Goodbye dlroW!';
+is render-template($test-file, {name => "dlroW"}), 'Goodbye dlroW!',
+        'Change was detected';
+
+my $used-file = $*PROGRAM.parent.add('test-data').add('reload-used.crotmp');
+END try unlink $used-file;
+$used-file.spurt: "<:sub foo>yes!</:>";
+my $using-file = $*PROGRAM.parent.add('test-data').add('reload-using.crotmp');
+END try unlink $using-file;
+$using-file.spurt: "<:use 'reload-used.crotmp'><&foo>";
+template-location $*PROGRAM.parent.add('test-data');
+is render-template($using-file, {}), 'yes!',
+        'Correct rendering involving `use` before change';
+
+$used-file.spurt: "<:sub foo>no!</:>";
+is render-template($using-file, {}), 'no!',
+        'Change in used module was detected';