Require colon in show rule

13 files changed, 38 insertions, 29 deletions

diff --git a/docs/src/reference/styling.md b/docs/src/reference/styling.md
index 92b5f8c9..8e3937b4 100644
--- a/docs/src/reference/styling.md
+++ b/docs/src/reference/styling.md
@@ -110,7 +110,7 @@ element. And apart from a function, the left-hand side of a show rule can also
 take a number of other _selectors_ that define what to apply the transformation
 to:
 
-- **Everything:** `{show rest => ..}` \
+- **Everything:** `{show: rest => ..}` \
   Transform everything after the show rule. This is useful to apply a more
   complex layout to your whole document without wrapping everything in a giant
   function call.
diff --git a/docs/src/reference/syntax.md b/docs/src/reference/syntax.md
index b4d14e01..422c035f 100644
--- a/docs/src/reference/syntax.md
+++ b/docs/src/reference/syntax.md
@@ -89,8 +89,9 @@ a table listing all syntax that is available in code mode:
 | Named function           | `{let f(x) = 2 * x}`          | [Function]($type/function)           |
 | Set rule                 | `{set text(14pt)}`            | [Styling]($styling/#set-rules)        |
 | Set-if rule              | `{set text(..) if .. }`       | [Styling]($styling/#set-rules)        |
-| Show rule                | `{show raw: it => {..}}`      | [Styling]($styling/#set-rules)        |
 | Show-set rule            | `{show par: set block(..)}`   | [Styling]($styling/#show-rules)       |
+| Show rule with function  | `{show raw: it => {..}}`      | [Styling]($styling/#show-rules)        |
+| Show-everything rule     | `{show: columns.with(2)}`      | [Styling]($styling/#show-rules)        |
 | Conditional              | `{if x == 1 {..} else {..}}`  | [Scripting]($scripting/#conditionals) |
 | For loop                 | `{for x in (1, 2, 3) {..}}`   | [Scripting]($scripting/#loops)        |
 | While loop               | `{while x < 10 {..}}`         | [Scripting]($scripting/#loops)        |
diff --git a/docs/src/tutorial/3-advanced.md b/docs/src/tutorial/3-advanced.md
index 08a8e8f7..ab65008c 100644
--- a/docs/src/tutorial/3-advanced.md
+++ b/docs/src/tutorial/3-advanced.md
@@ -268,11 +268,11 @@ abstract to be in two columns, we need to apply the column function to our whole
 document.
 
 Instead of wrapping the whole document in a giant function call, we can use an
-"everything" show rule. This show rule does not feature a colon. Instead, we
-directly provide a function that is given the rest of the document as a
-parameter. We have called the parameter `rest` here, but you are free to choose
-any name. The rule can then do anything with this content. In our case, it
-passes it on to the `columns` function.
+"everything" show rule. To write such a show rule, put a colon directly behind
+the show keyword and then provide a function. This function is given the rest of
+the document as a parameter. We have called the parameter `rest` here, but you
+are free to choose any name. The function can then do anything with this
+content. In our case, it passes it on to the `columns` function.
 
 ```example
 >>> #let title = [
@@ -323,7 +323,7 @@ passes it on to the `columns` function.
 >>> #v(4mm)
 <<< ...
 
-#show rest => columns(2, rest)
+#show: rest => columns(2, rest)
 
 = Introduction
 #lorem(300)
@@ -391,7 +391,7 @@ a way to set any of that, we need to write our own heading show rule.
 >>> ]
 >>>
 >>> #v(4mm)
->>> #show rest => columns(2, rest)
+>>> #show: rest => columns(2, rest)
 >>>
 >>> = Introduction
 >>> #lorem(35)
@@ -480,7 +480,7 @@ differentiate between section and subsection headings:
 >>> ]
 >>>
 >>> #v(4mm)
->>> #show rest => columns(2, rest)
+>>> #show: rest => columns(2, rest)
 >>>
 >>> = Introduction
 >>> #lorem(35)
diff --git a/docs/src/tutorial/4-template.md b/docs/src/tutorial/4-template.md
index bf2fd3b1..6b176d32 100644
--- a/docs/src/tutorial/4-template.md
+++ b/docs/src/tutorial/4-template.md
@@ -48,7 +48,7 @@ function to our whole document. Let's do that with our `amazed` function.
 >>> #let amazed(term, color: blue) = {
 >>>   text(color, box[✨ #term ✨])
 >>> }
-#show amazed
+#show: amazed
 I choose to focus on the good
 in my life and let go of any
 negative thoughts or beliefs.
@@ -72,7 +72,7 @@ that content block.
   #doc
 ]
 
-#show template
+#show: template
 I am learning something cool today.
 It's going great so far!
 ```
@@ -125,7 +125,7 @@ previous chapter.
   columns(2, doc)
 }
 
-#show doc => conf([Paper title], doc)
+#show: doc => conf([Paper title], doc)
 
 = Introduction
 #lorem(90)
@@ -161,7 +161,7 @@ things readable, we'll add those as named arguments. In the end, we want it to
 work like this:
 
 ```typ
-#show doc => conf(
+#show: doc => conf(
   title: [Towards Improved Modelling],
   authors: (
     (
@@ -324,7 +324,7 @@ path of the file after the `{from}` keyword.
 >>>}
 <<< #import "conf.typ": conf
 
-#show doc => conf(
+#show: doc => conf(
   title: [
     Towards Improved Modelling
   ],
diff --git a/src/ide/complete.rs b/src/ide/complete.rs
index d6879cca..8db1bf82 100644
--- a/src/ide/complete.rs
+++ b/src/ide/complete.rs
@@ -724,6 +724,12 @@ fn code_completions(ctx: &mut CompletionContext, hashtag: bool) {
     );
 
     ctx.snippet_completion(
+        "show rule (everything)",
+        "show: ${}",
+        "Transforms everything that follows.",
+    );
+
+    ctx.snippet_completion(
         "let binding",
         "let ${name} = ${value}",
         "Saves a value in a variable.",
diff --git a/src/ide/highlight.rs b/src/ide/highlight.rs
index c12cb87a..7827b2c9 100644
--- a/src/ide/highlight.rs
+++ b/src/ide/highlight.rs
@@ -279,9 +279,10 @@ fn highlight_ident(node: &LinkedNode) -> Option<Tag> {
         ancestor = ancestor.parent()?;
     }
 
-    // Are we directly before a show rule colon?
-    if next_leaf.map(|leaf| leaf.kind()) == Some(SyntaxKind::Colon)
-        && ancestor.parent_kind() == Some(SyntaxKind::ShowRule)
+    // Are we directly before or behind a show rule colon?
+    if ancestor.parent_kind() == Some(SyntaxKind::ShowRule)
+        && (next_leaf.map(|leaf| leaf.kind()) == Some(SyntaxKind::Colon)
+            || node.prev_leaf().map(|leaf| leaf.kind()) == Some(SyntaxKind::Colon))
     {
         return Some(Tag::Function);
     }
diff --git a/src/syntax/parser.rs b/src/syntax/parser.rs
index 8082fd64..cd318983 100644
--- a/src/syntax/parser.rs
+++ b/src/syntax/parser.rs
@@ -852,10 +852,11 @@ fn set_rule(p: &mut Parser) {
 fn show_rule(p: &mut Parser) {
     let m = p.marker();
     p.assert(SyntaxKind::Show);
-    code_expr(p);
-    if p.eat_if(SyntaxKind::Colon) {
+    if !p.at(SyntaxKind::Colon) {
         code_expr(p);
     }
+    p.expect(SyntaxKind::Colon);
+    code_expr(p);
     p.wrap(m, SyntaxKind::ShowRule);
 }
 
diff --git a/tests/ref/compiler/highlight.png b/tests/ref/compiler/highlight.png
index 236a09cb..18e52dc5 100644
--- a/tests/ref/compiler/highlight.png
+++ b/tests/ref/compiler/highlight.png
diff --git a/tests/ref/text/raw-code.png b/tests/ref/text/raw-code.png
index e0387870..a326b41e 100644
--- a/tests/ref/text/raw-code.png
+++ b/tests/ref/text/raw-code.png
diff --git a/tests/typ/compiler/break-continue.typ b/tests/typ/compiler/break-continue.typ
index e1041551..d4bd01e3 100644
--- a/tests/typ/compiler/break-continue.typ
+++ b/tests/typ/compiler/break-continue.typ
@@ -116,7 +116,7 @@
 // Everything should be in smallcaps.
 #for color in (red, blue, green, yellow) [
   #set text("Roboto")
-  #show it => text(fill: color, it)
+  #show: it => text(fill: color, it)
   #smallcaps(if color != green [
     Some
   ] else [
diff --git a/tests/typ/compiler/show-bare.typ b/tests/typ/compiler/show-bare.typ
index 2f076ade..0558fc44 100644
--- a/tests/typ/compiler/show-bare.typ
+++ b/tests/typ/compiler/show-bare.typ
@@ -9,25 +9,25 @@
   T. Ypst
 ]
 
-#show columns.with(2)
+#show: columns.with(2)
 Great typography is at the essence of great storytelling. It is the medium that
 transports meaning from parchment to reader, the wave that sparks a flame
 in booklovers and the great fulfiller of human need.
 
 ---
 // Test bare show in content block.
-A #[_B #show c => [*#c*]; C_] D
+A #[_B #show: c => [*#c*]; C_] D
 
 ---
 // Test style precedence.
 #set text(fill: eastern, size: 1.5em)
-#show text.with(fill: forest)
+#show: text.with(fill: forest)
 Forest
 
 ---
-#show [Shown]
+#show: [Shown]
 Ignored
 
 ---
-// Error: 5-19 show is only allowed directly in code and content blocks
-#{ (show body => 2) * body }
+// Error: 5-20 show is only allowed directly in code and content blocks
+#{ (show: body => 2) * body }
diff --git a/tests/typ/compiler/show-node.typ b/tests/typ/compiler/show-node.typ
index f6298a28..09481957 100644
--- a/tests/typ/compiler/show-node.typ
+++ b/tests/typ/compiler/show-node.typ
@@ -64,7 +64,7 @@ Another text.
   world
   {
     set text(blue)
-    show it => {
+    show: it => {
       show "o": "Ø"
       it
     }
diff --git a/tests/typ/visualize/shape-circle.typ b/tests/typ/visualize/shape-circle.typ
index 94facdeb..cde4b112 100644
--- a/tests/typ/visualize/shape-circle.typ
+++ b/tests/typ/visualize/shape-circle.typ
@@ -40,7 +40,7 @@ Expanded by height.
 ---
 // Test relative sizing.
 #set text(fill: white)
-#show rect.with(width: 100pt, height: 50pt, inset: 0pt, fill: rgb("aaa"))
+#show: rect.with(width: 100pt, height: 50pt, inset: 0pt, fill: rgb("aaa"))
 #set align(center + horizon)
 #stack(
   dir: ltr,