From ca2fcdbedec701960915d137e10068766068c3b1 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Wed, 4 Oct 2023 15:08:04 -0400
Subject: [PATCH] Highlight single-line comments (up to step 172)

---
 editor/document/row.go        | 17 ++++++++++++++++-
 editor/highlight/constants.go |  1 +
 editor/highlight/syntax.go    | 26 +++++++++++++++++---------
 3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/editor/document/row.go b/editor/document/row.go
index aa13b57..9b96ce9 100644
--- a/editor/document/row.go
+++ b/editor/document/row.go
@@ -122,18 +122,32 @@ func (r *Row) updateSyntax() {
 		return
 	}
 
+	var scsIndex int = -1
+	scs := s.LineCommentStart
+	if len(scs) > 0 {
+		scsIndex = strings.Index(string(r.render), scs)
+	}
+
 	prevSep := true
 	inString := '0'
 	for i < r.RenderSize() {
 		ch := r.render[i]
 		prevHl := highlight.Normal
-
 		if i > 0 {
 			prevHl = r.Hl[i-1]
 		}
 
 		ip1 := i + 1
 
+		// Single line comments
+		if inString == '0' && scsIndex == i {
+			for j := scsIndex; j < r.RenderSize(); j++ {
+				r.Hl[j] = highlight.Comment
+			}
+			break
+		}
+
+		// String literals
 		if s.Flags&highlight.HighlightStrings == highlight.HighlightStrings {
 			// At the start of a string literal
 			if inString == '0' && (ch == '"' || ch == '\'') {
@@ -166,6 +180,7 @@ func (r *Row) updateSyntax() {
 			}
 		}
 
+		// Numeric literals
 		if s.Flags&highlight.HighlightNumbers == highlight.HighlightNumbers {
 			if (unicode.IsDigit(ch) && (prevSep || prevHl == highlight.Number)) ||
 				(ch == '.' && prevHl == highlight.Number) {
diff --git a/editor/highlight/constants.go b/editor/highlight/constants.go
index 92dcf1f..d744e36 100644
--- a/editor/highlight/constants.go
+++ b/editor/highlight/constants.go
@@ -5,6 +5,7 @@ package highlight
 // ----------------------------------------------------------------------------
 const (
 	Normal = iota
+	Comment
 	String
 	Number
 	Match
diff --git a/editor/highlight/syntax.go b/editor/highlight/syntax.go
index dabd12b..4d85bf1 100644
--- a/editor/highlight/syntax.go
+++ b/editor/highlight/syntax.go
@@ -10,10 +10,11 @@ import (
 // ------------------------------------------------------------------
 
 var syntaxColorMap = map[int]string{
-	String: terminal.FGMagenta,
-	Number: terminal.FGRed,
-	Match:  terminal.FGBlue,
-	Normal: terminal.DefaultFGColor,
+	Comment: terminal.FGCyan,
+	String:  terminal.FGMagenta,
+	Number:  terminal.FGRed,
+	Match:   terminal.FGBlue,
+	Normal:  terminal.DefaultFGColor,
 }
 
 // SyntaxToColor Take a highlighting type and map it to
@@ -32,23 +33,27 @@ func SyntaxToColor(hl int) string {
 // ------------------------------------------------------------------
 
 type Syntax struct {
-	FileType  string
-	FileMatch []string
-	Flags     int
+	FileType         string
+	FileMatch        []string
+	LineCommentStart string
+	Flags            int
 }
 
 // HLDB - The "database" of syntax types
 var HLDB = []*Syntax{{
 	"c",
 	[]string{".c", ".h", ".cpp"},
+	"//",
 	HighlightNumbers | HighlightStrings,
 }, {
 	"go",
 	[]string{".go", "go.mod"},
+	"//",
 	HighlightNumbers | HighlightStrings,
 }, {
 	"makefile",
-	[]string{"Makefile", "makefile"},
+	[]string{"Makefile", "makefile", "justfile"},
+	"#",
 	0,
 }}
 
@@ -57,8 +62,11 @@ func GetSyntaxByFilename(filename string) *Syntax {
 		return nil
 	}
 
+	var ext string = ""
 	extInd := strings.LastIndex(filename, ".")
-	ext := filename[extInd:len(filename)]
+	if extInd > -1 {
+		ext = filename[extInd:len(filename)]
+	}
 
 	for i := 0; i < len(HLDB); i++ {
 		s := HLDB[i]