From 176b070c779ef8aa4515c8ff062b17ca9114fd3f Mon Sep 17 00:00:00 2001
From: Laurenz <laurmaedje@gmail.com>
Date: Fri, 24 Jan 2025 13:31:03 +0100
Subject: [PATCH] Fix space collapsing for explicit paragraphs (#5749)

---
 crates/typst-realize/src/lib.rs       |   4 +--
 tests/ref/par-contains-block.png      | Bin 426 -> 423 bytes
 tests/ref/par-contains-parbreak.png   | Bin 426 -> 423 bytes
 tests/ref/par-explicit-trim-space.png | Bin 0 -> 215 bytes
 tests/ref/par-show-children.png       | Bin 0 -> 920 bytes
 tests/ref/par-show-styles.png         | Bin 0 -> 471 bytes
 tests/ref/par-show.png                | Bin 932 -> 0 bytes
 tests/suite/model/par.typ             |  37 +++++++++++++++++++++-----
 8 files changed, 32 insertions(+), 9 deletions(-)
 create mode 100644 tests/ref/par-explicit-trim-space.png
 create mode 100644 tests/ref/par-show-children.png
 create mode 100644 tests/ref/par-show-styles.png
 delete mode 100644 tests/ref/par-show.png

diff --git a/crates/typst-realize/src/lib.rs b/crates/typst-realize/src/lib.rs
index 754e89aac..50685a962 100644
--- a/crates/typst-realize/src/lib.rs
+++ b/crates/typst-realize/src/lib.rs
@@ -729,8 +729,8 @@ fn finish(s: &mut State) -> SourceResult<()> {
         }
     })?;
 
-    // In math, spaces are top-level.
-    if let RealizationKind::Math = s.kind {
+    // In paragraph and math realization, spaces are top-level.
+    if matches!(s.kind, RealizationKind::LayoutPar | RealizationKind::Math) {
         collapse_spaces(&mut s.sink, 0);
     }
 
diff --git a/tests/ref/par-contains-block.png b/tests/ref/par-contains-block.png
index f4bd071f62fe2e7ee6eee07dff9f8d71301dbbc1..27ca0cf6b0cb79a4f2fc573d20054596bd009117 100644
GIT binary patch
delta 397
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zip5KnR{uY3Ui=5dZma!hbps*QZTtF^(e(dU-Oj=+j@Sew%loL~V?`hiIuB;<tot8(
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delta 400
zcmV;B0dM}N1F8d%B!6*9L_t(|+U?XmOG057#_>KzW7Jfe5)FbR1U5yX6h#CE4M9Og
zO5_V+m`0k}n}$h&31JyVxEQnvrDlS8Pzr^}FtQ-fl2ab9L^**=iwA-_|Mhy{2hVWV
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diff --git a/tests/ref/par-contains-parbreak.png b/tests/ref/par-contains-parbreak.png
index f4bd071f62fe2e7ee6eee07dff9f8d71301dbbc1..27ca0cf6b0cb79a4f2fc573d20054596bd009117 100644
GIT binary patch
delta 397
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zip5KnR{uY3Ui=5dZma!hbps*QZTtF^(e(dU-Oj=+j@Sew%loL~V?`hiIuB;<tot8(
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delta 400
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diff --git a/tests/ref/par-explicit-trim-space.png b/tests/ref/par-explicit-trim-space.png
new file mode 100644
index 0000000000000000000000000000000000000000..ff542274ade651170352f1be82314ea55f9d9365
GIT binary patch
literal 215
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literal 0
HcmV?d00001

diff --git a/tests/ref/par-show-children.png b/tests/ref/par-show-children.png
new file mode 100644
index 0000000000000000000000000000000000000000..bc81c5bdc9464eed1941fbe5809db05bde1defc3
GIT binary patch
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diff --git a/tests/ref/par-show-styles.png b/tests/ref/par-show-styles.png
new file mode 100644
index 0000000000000000000000000000000000000000..13a8065ad3b7cb1111ac7e78320a75218fdd37bb
GIT binary patch
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diff --git a/tests/ref/par-show.png b/tests/ref/par-show.png
deleted file mode 100644
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GIT binary patch
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diff --git a/tests/suite/model/par.typ b/tests/suite/model/par.typ
index 84f2ec152..fa230451d 100644
--- a/tests/suite/model/par.typ
+++ b/tests/suite/model/par.typ
@@ -215,14 +215,16 @@ Welcome \ here. Does this work well?
 #set text(hyphenate: false)
 Lorem ipsum dolor #metadata(none) nonumy eirmod tempor.
 
---- par-show ---
-// This is only slightly cursed.
-#let revoke = metadata("revoke")
+--- par-show-children ---
+// Variant 1: Prevent recursion by checking the children.
+#let p = counter("p")
+#let step = p.step()
+#let nr = context p.display()
 #show par: it => {
-  if bibliography.title == revoke { return it }
-  set bibliography(title: revoke)
-  let p = counter("p")
-  par[#p.step() §#context p.display() #it.body]
+  if it.body.at("children", default: ()).at(0, default: none) == step {
+    return it
+  }
+  par(step + [§#nr ] + it.body)
 }
 
 = A
@@ -235,6 +237,27 @@ C #parbreak() D
 
 #block[F #parbreak() G]
 
+--- par-show-styles ---
+// Variant 2: Prevent recursion by observing a style.
+#let revoke = metadata("revoke")
+#show par: it => {
+  if bibliography.title == revoke { return it }
+  set bibliography(title: revoke)
+  let p = counter("p")
+  par[#p.step()§#context p.display() #it.body]
+}
+
+= A
+
+B
+
+C
+
+--- par-explicit-trim-space ---
+A
+
+#par[ B ]
+
 --- issue-4278-par-trim-before-equation ---
 #set par(justify: true)
 #lorem(6) aa $a = c + b$