From 5b742594cc1a8cb86d260546a14cf877c0feacf3 Mon Sep 17 00:00:00 2001
From: Christian Muehlhaeuser <muesli@gmail.com>
Date: Mon, 16 Dec 2019 08:37:31 +0100
Subject: [PATCH] Automatically apply custom chroma theme when set in style

---
 ansi/codeblock.go | 71 ++++++++++++++++++++++++-----------------------
 ansi/style.go     |  2 +-
 2 files changed, 38 insertions(+), 35 deletions(-)

diff --git a/ansi/codeblock.go b/ansi/codeblock.go
index a8e5fe7..b00a07e 100644
--- a/ansi/codeblock.go
+++ b/ansi/codeblock.go
@@ -63,40 +63,43 @@ func (e *CodeBlockElement) Render(w io.Writer, ctx RenderContext) error {
 	}
 	theme := rules.Theme
 
-	styles.Register(chroma.MustNewStyle("charm",
-		chroma.StyleEntries{
-			chroma.Text:                chromaStyle(rules.Chroma.Text),
-			chroma.Error:               chromaStyle(rules.Chroma.Error),
-			chroma.Comment:             chromaStyle(rules.Chroma.Comment),
-			chroma.CommentPreproc:      chromaStyle(rules.Chroma.CommentPreproc),
-			chroma.Keyword:             chromaStyle(rules.Chroma.Keyword),
-			chroma.KeywordReserved:     chromaStyle(rules.Chroma.KeywordReserved),
-			chroma.KeywordNamespace:    chromaStyle(rules.Chroma.KeywordNamespace),
-			chroma.KeywordType:         chromaStyle(rules.Chroma.KeywordType),
-			chroma.Operator:            chromaStyle(rules.Chroma.Operator),
-			chroma.Punctuation:         chromaStyle(rules.Chroma.Punctuation),
-			chroma.Name:                chromaStyle(rules.Chroma.Name),
-			chroma.NameBuiltin:         chromaStyle(rules.Chroma.NameBuiltin),
-			chroma.NameTag:             chromaStyle(rules.Chroma.NameTag),
-			chroma.NameAttribute:       chromaStyle(rules.Chroma.NameAttribute),
-			chroma.NameClass:           chromaStyle(rules.Chroma.NameClass),
-			chroma.NameConstant:        chromaStyle(rules.Chroma.NameConstant),
-			chroma.NameDecorator:       chromaStyle(rules.Chroma.NameDecorator),
-			chroma.NameException:       chromaStyle(rules.Chroma.NameException),
-			chroma.NameFunction:        chromaStyle(rules.Chroma.NameFunction),
-			chroma.NameOther:           chromaStyle(rules.Chroma.NameOther),
-			chroma.Literal:             chromaStyle(rules.Chroma.Literal),
-			chroma.LiteralNumber:       chromaStyle(rules.Chroma.LiteralNumber),
-			chroma.LiteralDate:         chromaStyle(rules.Chroma.LiteralDate),
-			chroma.LiteralString:       chromaStyle(rules.Chroma.LiteralString),
-			chroma.LiteralStringEscape: chromaStyle(rules.Chroma.LiteralStringEscape),
-			chroma.GenericDeleted:      chromaStyle(rules.Chroma.GenericDeleted),
-			chroma.GenericEmph:         chromaStyle(rules.Chroma.GenericEmph),
-			chroma.GenericInserted:     chromaStyle(rules.Chroma.GenericInserted),
-			chroma.GenericStrong:       chromaStyle(rules.Chroma.GenericStrong),
-			chroma.GenericSubheading:   chromaStyle(rules.Chroma.GenericSubheading),
-			chroma.Background:          chromaStyle(rules.Chroma.Background),
-		}))
+	if rules.Chroma != nil {
+		theme = "charm"
+		styles.Register(chroma.MustNewStyle("charm",
+			chroma.StyleEntries{
+				chroma.Text:                chromaStyle(rules.Chroma.Text),
+				chroma.Error:               chromaStyle(rules.Chroma.Error),
+				chroma.Comment:             chromaStyle(rules.Chroma.Comment),
+				chroma.CommentPreproc:      chromaStyle(rules.Chroma.CommentPreproc),
+				chroma.Keyword:             chromaStyle(rules.Chroma.Keyword),
+				chroma.KeywordReserved:     chromaStyle(rules.Chroma.KeywordReserved),
+				chroma.KeywordNamespace:    chromaStyle(rules.Chroma.KeywordNamespace),
+				chroma.KeywordType:         chromaStyle(rules.Chroma.KeywordType),
+				chroma.Operator:            chromaStyle(rules.Chroma.Operator),
+				chroma.Punctuation:         chromaStyle(rules.Chroma.Punctuation),
+				chroma.Name:                chromaStyle(rules.Chroma.Name),
+				chroma.NameBuiltin:         chromaStyle(rules.Chroma.NameBuiltin),
+				chroma.NameTag:             chromaStyle(rules.Chroma.NameTag),
+				chroma.NameAttribute:       chromaStyle(rules.Chroma.NameAttribute),
+				chroma.NameClass:           chromaStyle(rules.Chroma.NameClass),
+				chroma.NameConstant:        chromaStyle(rules.Chroma.NameConstant),
+				chroma.NameDecorator:       chromaStyle(rules.Chroma.NameDecorator),
+				chroma.NameException:       chromaStyle(rules.Chroma.NameException),
+				chroma.NameFunction:        chromaStyle(rules.Chroma.NameFunction),
+				chroma.NameOther:           chromaStyle(rules.Chroma.NameOther),
+				chroma.Literal:             chromaStyle(rules.Chroma.Literal),
+				chroma.LiteralNumber:       chromaStyle(rules.Chroma.LiteralNumber),
+				chroma.LiteralDate:         chromaStyle(rules.Chroma.LiteralDate),
+				chroma.LiteralString:       chromaStyle(rules.Chroma.LiteralString),
+				chroma.LiteralStringEscape: chromaStyle(rules.Chroma.LiteralStringEscape),
+				chroma.GenericDeleted:      chromaStyle(rules.Chroma.GenericDeleted),
+				chroma.GenericEmph:         chromaStyle(rules.Chroma.GenericEmph),
+				chroma.GenericInserted:     chromaStyle(rules.Chroma.GenericInserted),
+				chroma.GenericStrong:       chromaStyle(rules.Chroma.GenericStrong),
+				chroma.GenericSubheading:   chromaStyle(rules.Chroma.GenericSubheading),
+				chroma.Background:          chromaStyle(rules.Chroma.Background),
+			}))
+	}
 
 	iw := &indent.Writer{
 		Indent: indentation + margin,
diff --git a/ansi/style.go b/ansi/style.go
index 1e7f251..1335ad5 100644
--- a/ansi/style.go
+++ b/ansi/style.go
@@ -38,7 +38,7 @@ type StyleBlock struct {
 type StyleCodeBlock struct {
 	StyleBlock
 	Theme  string `json:"theme"`
-	Chroma struct {
+	Chroma *struct {
 		Text                StylePrimitive `json:"text"`
 		Error               StylePrimitive `json:"error"`
 		Comment             StylePrimitive `json:"comment"`