Greatly expand the explicit_context_setting test.

Turns out explicit context setting works in a lot more places than the official dustjs pages indicate. Also some things don't make much sense (like setting it on a block works but not on an inline partial).

js/test_cases/explicit_context_setting/README.md

@@ -1 +1,40 @@
-It seems $idx and $len do not survive through an explicit context setting, which will work perfectly with my injected-context architecture.
+$idx and $len
+-------------
+
+$idx and $len do not survive through an explicit context setting, which will work perfectly with my injected-context architecture.
+
+You can use $idx and $len as your explicit context, but as scalar values I do not think there is a way to access them anyway.
+
+Exists and Not-Exists
+=====================
+
+Looks like you can exlicitly set a context with exists and not-exists tags too. This works out well in the parser because I am using the same code for those blocks.
+
+Partials
+--------
+
+Explicitly setting a context in a partial also works. The explicit context takes priority over the parameters in the partial tag.
+
+This works for both regular named partials and quoted partials.
+
+Helpers
+-------
+
+Explicitly setting a context in a helper works too.
+
+Blocks and Inline Partials
+--------------------------
+
+Explicitly setting a context on an inline partial does not work, but it does not error out either, so I need to add support for this in the parser.
+
+Explicitly setting a context on a block does work.
+
+References
+----------
+
+Explicitly setting a context does not work on a reference, but it has revealed that invalid dust is rendered verbatim. I'm going to leave that commented out until I can address that in a later branch.
+
+Paths
+-----
+
+Explicit contexts do support deep paths

js/test_cases/explicit_context_setting/default.dust

@@ -0,0 +1 @@
+{+pet_line}BLOCK {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}{/pet_line}

js/test_cases/explicit_context_setting/default_explicit.dust

@@ -0,0 +1 @@
+{+pet_line:explicit}BLOCK {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}{/pet_line}

js/test_cases/explicit_context_setting/input1.json

@@ -19,5 +19,10 @@
   ],
   "explicit": {
     "pet": "cat"
+  },
+  "deep_explicit": {
+    "explicit": {
+      "pet": "cat"
+    }
   }
 }

js/test_cases/explicit_context_setting/main.dust

@@ -1,4 +1,6 @@
 {! First we do it without explicit context setting which results in being able to read some_global but not pet !}
+Section Regular{~n}
+==============={~n}
 {#loop}
     {#person}
         {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
@@ -6,8 +8,152 @@
 {/loop}
 
 {! Then we do it with explicit context setting which should result in being able ot read pet but not some_global !}
+Section Explicit{~n}
+================{~n}
 {#loop}
     {#person:explicit}
         {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
     {/person}
 {/loop}
+
+{! What happens if we try to use an explicit context with an exists block instead of a section !}
+Exists Regular{~n}
+=============={~n}
+{#loop}
+    {?person}
+        {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+
+Exists Explicit{~n}
+==============={~n}
+{#loop}
+    {?person:explicit}
+        {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+
+{! Can you explicitly set the context for a partial? !}
+Partial Regular{~n}
+==============={~n}
+{#loop}
+    {>other/}
+{/loop}
+
+Partial Explicit{~n}
+================{~n}
+{#loop}
+    {>other:explicit/}
+{/loop}
+
+Quoted Partial Explicit{~n}
+======================={~n}
+{#loop}
+    {>"other":explicit/}
+{/loop}
+
+Partial Regular with parameters{~n}
+==============================={~n}
+{#loop}
+    {>other pet="rabbit"/}
+{/loop}
+
+Partial Explicit with parameters{~n}
+================================{~n}
+{#loop}
+    {>other:explicit pet="rabbit"/}
+{/loop}
+
+{! Can you explicitly set the context for a helper? !}
+Helper Regular{~n}
+=============={~n}
+{#loop}
+    {@eq key="foo" value="foo"}
+        {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}
+    {/eq}
+{/loop}
+
+Helper Explicit{~n}
+==============={~n}
+{#loop}
+    {@eq:explicit key="foo" value="foo"}
+        {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}
+    {/eq}
+{/loop}
+
+{! Can you explicitly set the context for inline partials or blocks? !}
+Block Regular{~n}
+============={~n}
+{#loop}
+    {>default/}
+{/loop}
+
+Inline Partial Regular{~n}
+======================{~n}
+{#loop}
+    {>override/}
+{/loop}
+
+Block Explicit{~n}
+=============={~n}
+{#loop}
+    {>default_explicit/}
+{/loop}
+
+Inline Partial Explicit{~n}
+======================={~n}
+{#loop}
+    {>override_explicit/}
+{/loop}
+
+Inline Partial and Block Explicit{~n}
+================================={~n}
+{#loop}
+    {>override_double_explicit/}
+{/loop}
+
+{! Can you explicitly set the context for references? !}
+{! Commented out until I add support for rendering invalid dust verbatim
+Reference Regular{~n}
+================={~n}
+{.}{~n}
+
+Reference Explicit{~n}
+=================={~n}
+{.:some_global}{~n}
+!}
+
+{! Can you explicitly set the context with a path? !}
+Path Regular{~n}
+============{~n}
+{#loop}
+    {#person}
+        {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+
+Path Explicit{~n}
+============={~n}
+{#loop}
+    {#person:deep_explicit.explicit}
+        {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+
+{! Can you explicitly set the context to a variable? !}
+Variable Regular{~n}
+================{~n}
+{#loop}
+    {#person}
+        {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+
+Variable Explicit{~n}
+================={~n}
+{#loop}
+    {#person:$idx}
+        {$idx}: {name} has a pet {pet} but not a {some_global}{~n}
+    {/person}
+{/loop}
+

js/test_cases/explicit_context_setting/other.dust

@@ -0,0 +1 @@
+{$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}

js/test_cases/explicit_context_setting/override.dust

@@ -0,0 +1,2 @@
+{>default/}
+{<pet_line}INLINE PARTIAL {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}{/pet_line}

js/test_cases/explicit_context_setting/override_double_explicit.dust

@@ -0,0 +1,2 @@
+{>default_explicit/}
+{<pet_line:explicit}INLINE PARTIAL {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}{/pet_line}

js/test_cases/explicit_context_setting/override_explicit.dust

@@ -0,0 +1,2 @@
+{>default/}
+{<pet_line:explicit}INLINE PARTIAL {$idx}: {person.name} has a pet {pet} but not a {some_global}{~n}{/pet_line}

src/parser/parser.rs

@@ -341,14 +341,16 @@ where
     F: Fn(Container<'a>) -> DustTag<'a>,
 {
     move |i: &'a str| {
-        let (i, (opening_name, inner, maybe_else, _closing_name)) = verify(
+        let (i, (opening_name, maybe_explicit_context, inner, maybe_else, _closing_name)) =
+            verify(
                 tuple((
-                delimited(tag(open_matcher), path, tag("}")),
+                    preceded(tag(open_matcher), path),
+                    terminated(opt(preceded(tag(":"), path)), tag("}")),
                     opt(body),
                     opt(preceded(tag("{:else}"), opt(body))),
                     delimited(tag("{/"), path, tag("}")),
                 )),
-            |(open, _inn, _maybe_else, close)| open == close,
+                |(open, _maybe_explicit, _inn, _maybe_else, close)| open == close,
             )(i)?;
 
         Ok((