From b51bc605b887b62960d0b0308cbf20839a39608e Mon Sep 17 00:00:00 2001
From: Evan Wallace <evan.exe@gmail.com>
Date: Thu, 11 Mar 2021 19:18:33 -0800
Subject: [PATCH] fix #955: support css page margin rules

---
 CHANGELOG.md                           |  4 ++
 internal/css_parser/css_parser.go      | 18 ++++++
 internal/css_parser/css_parser_test.go | 76 ++++++++++++++++++++++++++
 3 files changed, 98 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 90c2bc1d9d4..0fc24249717 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,10 @@
     ({x, ...y} = {x: 1, y: 2})
     ```
 
+* Basic support for CSS page margin rules ([#955](https://github.com/evanw/esbuild/issues/955))
+
+    There are 16 different special at-rules that can be nested inside the `@page` rule. They are defined in [this specification](https://www.w3.org/TR/css-page-3/#syntax-page-selector). Previously esbuild treated these as unknown rules, but with this release esbuild will now treat these as known rules. The only real difference in behavior is that esbuild will no longer warn about these rules being unknown.
+
 ## 0.9.0
 
 **This release contains backwards-incompatible changes.** Since esbuild is before version 1.0.0, these changes have been released as a new minor version to reflect this (as [recommended by npm](https://docs.npmjs.com/cli/v6/using-npm/semver/)). You should either be pinning the exact version of `esbuild` in your `package.json` file or be using a version range syntax that only accepts patch upgrades such as `^0.8.0`. See the documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.
diff --git a/internal/css_parser/css_parser.go b/internal/css_parser/css_parser.go
index 5d1370657ca..a0a7f726dab 100644
--- a/internal/css_parser/css_parser.go
+++ b/internal/css_parser/css_parser.go
@@ -297,6 +297,24 @@ var specialAtRules = map[string]atRuleKind{
 	"font-face": atRuleDeclarations,
 	"page":      atRuleDeclarations,
 
+	// These go inside "@page": https://www.w3.org/TR/css-page-3/#syntax-page-selector
+	"bottom-center":       atRuleDeclarations,
+	"bottom-left-corner":  atRuleDeclarations,
+	"bottom-left":         atRuleDeclarations,
+	"bottom-right-corner": atRuleDeclarations,
+	"bottom-right":        atRuleDeclarations,
+	"left-bottom":         atRuleDeclarations,
+	"left-middle":         atRuleDeclarations,
+	"left-top":            atRuleDeclarations,
+	"right-bottom":        atRuleDeclarations,
+	"right-middle":        atRuleDeclarations,
+	"right-top":           atRuleDeclarations,
+	"top-center":          atRuleDeclarations,
+	"top-left-corner":     atRuleDeclarations,
+	"top-left":            atRuleDeclarations,
+	"top-right-corner":    atRuleDeclarations,
+	"top-right":           atRuleDeclarations,
+
 	"document": atRuleInheritContext,
 	"media":    atRuleInheritContext,
 	"scope":    atRuleInheritContext,
diff --git a/internal/css_parser/css_parser_test.go b/internal/css_parser/css_parser_test.go
index 18191abcbb4..c6c767cd330 100644
--- a/internal/css_parser/css_parser_test.go
+++ b/internal/css_parser/css_parser_test.go
@@ -677,6 +677,82 @@ func TestAtRule(t *testing.T) {
 	expectParseError(t, "@", "<stdin>: warning: Unexpected \"@\"\n")
 	expectParseError(t, "@;", "<stdin>: warning: Unexpected \"@\"\n")
 	expectParseError(t, "@{}", "<stdin>: warning: Unexpected \"@\"\n")
+
+	// https://www.w3.org/TR/css-page-3/#syntax-page-selector
+	expectPrinted(t, `
+		@page :first { margin: 0 }
+		@page {
+			@top-left-corner { content: 'tlc' }
+			@top-left { content: 'tl' }
+			@top-center { content: 'tc' }
+			@top-right { content: 'tr' }
+			@top-right-corner { content: 'trc' }
+			@bottom-left-corner { content: 'blc' }
+			@bottom-left { content: 'bl' }
+			@bottom-center { content: 'bc' }
+			@bottom-right { content: 'br' }
+			@bottom-right-corner { content: 'brc' }
+			@left-top { content: 'lt' }
+			@left-middle { content: 'lm' }
+			@left-bottom { content: 'lb' }
+			@right-top { content: 'rt' }
+			@right-middle { content: 'rm' }
+			@right-bottom { content: 'rb' }
+		}
+	`, `@page :first {
+  margin: 0;
+}
+@page {
+  @top-left-corner {
+    content: "tlc";
+  }
+  @top-left {
+    content: "tl";
+  }
+  @top-center {
+    content: "tc";
+  }
+  @top-right {
+    content: "tr";
+  }
+  @top-right-corner {
+    content: "trc";
+  }
+  @bottom-left-corner {
+    content: "blc";
+  }
+  @bottom-left {
+    content: "bl";
+  }
+  @bottom-center {
+    content: "bc";
+  }
+  @bottom-right {
+    content: "br";
+  }
+  @bottom-right-corner {
+    content: "brc";
+  }
+  @left-top {
+    content: "lt";
+  }
+  @left-middle {
+    content: "lm";
+  }
+  @left-bottom {
+    content: "lb";
+  }
+  @right-top {
+    content: "rt";
+  }
+  @right-middle {
+    content: "rm";
+  }
+  @right-bottom {
+    content: "rb";
+  }
+}
+`)
 }
 
 func TestAtCharset(t *testing.T) {