colorscheme: Add capability to include schemes (#2844)

internal/config/colorscheme.go

@@ -52,51 +52,86 @@ func InitColorscheme() error {
 	Colorscheme = make(map[string]tcell.Style)
 	DefStyle = tcell.StyleDefault
 
-	return LoadDefaultColorscheme()
+	c, err := LoadDefaultColorscheme()
+	if err == nil {
+		Colorscheme = c
+	}
+
+	return err
 }
 
 // LoadDefaultColorscheme loads the default colorscheme from $(ConfigDir)/colorschemes
-func LoadDefaultColorscheme() error {
-	return LoadColorscheme(GlobalSettings["colorscheme"].(string))
+func LoadDefaultColorscheme() (map[string]tcell.Style, error) {
+	var parsedColorschemes []string
+	return LoadColorscheme(GlobalSettings["colorscheme"].(string), &parsedColorschemes)
 }
 
 // LoadColorscheme loads the given colorscheme from a directory
-func LoadColorscheme(colorschemeName string) error {
+func LoadColorscheme(colorschemeName string, parsedColorschemes *[]string) (map[string]tcell.Style, error) {
+	c := make(map[string]tcell.Style)
 	file := FindRuntimeFile(RTColorscheme, colorschemeName)
 	if file == nil {
-		return errors.New(colorschemeName + " is not a valid colorscheme")
+		return c, errors.New(colorschemeName + " is not a valid colorscheme")
 	}
 	if data, err := file.Data(); err != nil {
-		return errors.New("Error loading colorscheme: " + err.Error())
+		return c, errors.New("Error loading colorscheme: " + err.Error())
 	} else {
-		Colorscheme, err = ParseColorscheme(string(data))
+		var err error
+		c, err = ParseColorscheme(file.Name(), string(data), parsedColorschemes)
 		if err != nil {
-			return err
+			return c, err
 		}
 	}
-	return nil
+	return c, nil
 }
 
 // ParseColorscheme parses the text definition for a colorscheme and returns the corresponding object
 // Colorschemes are made up of color-link statements linking a color group to a list of colors
 // For example, color-link keyword (blue,red) makes all keywords have a blue foreground and
 // red background
-func ParseColorscheme(text string) (map[string]tcell.Style, error) {
+func ParseColorscheme(name string, text string, parsedColorschemes *[]string) (map[string]tcell.Style, error) {
 	var err error
-	parser := regexp.MustCompile(`color-link\s+(\S*)\s+"(.*)"`)
-
+	colorParser := regexp.MustCompile(`color-link\s+(\S*)\s+"(.*)"`)
+	includeParser := regexp.MustCompile(`include\s+"(.*)"`)
 	lines := strings.Split(text, "\n")
-
 	c := make(map[string]tcell.Style)
 
+	if parsedColorschemes != nil {
+		*parsedColorschemes = append(*parsedColorschemes, name)
+	}
+
+lineLoop:
 	for _, line := range lines {
 		if strings.TrimSpace(line) == "" ||
 			strings.TrimSpace(line)[0] == '#' {
 			// Ignore this line
 			continue
 		}
 
-		matches := parser.FindSubmatch([]byte(line))
+		matches := includeParser.FindSubmatch([]byte(line))
+		if len(matches) == 2 {
+			// support includes only in case parsedColorschemes are given
+			if parsedColorschemes != nil {
+				include := string(matches[1])
+				for _, name := range *parsedColorschemes {
+					// check for circular includes...
+					if name == include {
+						// ...and prevent them
+						continue lineLoop
+					}
+				}
+				includeScheme, err := LoadColorscheme(include, parsedColorschemes)
+				if err != nil {
+					return c, err
+				}
+				for k, v := range includeScheme {
+					c[k] = v
+				}
+			}
+			continue
+		}
+
+		matches = colorParser.FindSubmatch([]byte(line))
 		if len(matches) == 3 {
 			link := string(matches[1])
 			colors := string(matches[2])

internal/config/colorscheme_test.go

@@ -65,7 +65,7 @@ color-link constant "#AE81FF,#282828"
 color-link constant.string "#E6DB74,#282828"
 color-link constant.string.char "#BDE6AD,#282828"`
 
-	c, err := ParseColorscheme(testColorscheme)
+	c, err := ParseColorscheme("testColorscheme", testColorscheme, nil)
 	assert.Nil(t, err)
 
 	fg, bg, _ := c["comment"].Decompose()

runtime/colorschemes/default.micro

@@ -1,34 +1 @@
-color-link default "#F8F8F2,#282828"
-color-link comment "#75715E,#282828"
-color-link identifier "#66D9EF,#282828"
-color-link constant "#AE81FF,#282828"
-color-link constant.string "#E6DB74,#282828"
-color-link constant.string.char "#BDE6AD,#282828"
-color-link statement "#F92672,#282828"
-color-link symbol.operator "#F92671,#282828"
-color-link preproc "#CB4B16,#282828"
-color-link type "#66D9EF,#282828"
-color-link special "#A6E22E,#282828"
-color-link underlined "#D33682,#282828"
-color-link error "bold #CB4B16,#282828"
-color-link todo "bold #D33682,#282828"
-color-link hlsearch "#282828,#E6DB74"
-color-link statusline "#282828,#F8F8F2"
-color-link tabbar "#282828,#F8F8F2"
-color-link indent-char "#505050,#282828"
-color-link line-number "#AAAAAA,#323232"
-color-link current-line-number "#AAAAAA,#282828"
-color-link diff-added "#00AF00"
-color-link diff-modified "#FFAF00"
-color-link diff-deleted "#D70000"
-color-link gutter-error "#CB4B16,#282828"
-color-link gutter-warning "#E6DB74,#282828"
-color-link cursor-line "#323232"
-color-link color-column "#323232"
-#No extended types; Plain brackets.
-color-link type.extended "default"
-#color-link symbol.brackets "default"
-color-link symbol.tag "#AE81FF,#282828"
-color-link match-brace "#282828,#AE81FF"
-color-link tab-error "#D75F5F"
-color-link trailingws "#D75F5F"
+include "monokai"

runtime/help/colors.md

@@ -236,7 +236,10 @@ Here's a list of subgroups used in micro's built-in syntax files.
 * type.keyword (If you want a special highlight for keywords like `private`)
 
 In the future, plugins may also be able to use color groups for styling.
-
+Last but not least it's even possible to use `include` followed by the
+colorscheme name as string to include a different colorscheme within a new one.
+Additionally the groups can then be extended or overwritten. The `default.micro`
+theme can be seen as an example, which links to the chosen default colorscheme.
 
 ## Syntax files