Commits
Diff
package element
import (
"strconv"
"strings"
)
func Expander(styles map[string]string) map[string]string {
parsed := parseBackground(styles["background"])
delete(styles, "background")
// Print result
for key, value := range parsed {
if value != "" {
styles[key] = value
}
}
if styles["margin"] != "" {
left, right, top, bottom := convertMarginToIndividualProperties(styles["margin"])
if styles["margin-left"] == "" {
styles["margin-left"] = left
}
if styles["margin-right"] == "" {
styles["margin-right"] = right
}
if styles["margin-top"] == "" {
styles["margin-top"] = top
}
if styles["margin-bottom"] == "" {
styles["margin-bottom"] = bottom
}
}
delete(styles, "margin")
if styles["padding"] != "" {
left, right, top, bottom := convertMarginToIndividualProperties(styles["padding"])
if styles["padding-left"] == "" {
styles["padding-left"] = left
}
if styles["padding-right"] == "" {
styles["padding-right"] = right
}
if styles["padding-top"] == "" {
styles["padding-top"] = top
}
if styles["padding-bottom"] == "" {
styles["padding-bottom"] = bottom
}
}
delete(styles, "padding")
flex := parseFlex(styles["flex"])
delete(styles, "flex")
styles["flex-basis"] = flex.FlexBasis
styles["flex-grow"] = flex.FlexGrow
styles["flex-shrink"] = flex.FlexShrink
return styles
}
func convertMarginToIndividualProperties(margin string) (string, string, string, string) {
parts := strings.Fields(margin)
switch len(parts) {
case 1:
return parts[0], parts[0], parts[0], parts[0]
case 2:
return parts[0], parts[1], parts[0], parts[1]
case 3:
return parts[0], parts[1], parts[2], parts[1]
case 4:
return parts[0], parts[1], parts[2], parts[3]
}
return "0px", "0px", "0px", "0px"
}
// ParseBackground takes a CSS background shorthand and returns a map of its component parts.
func parseBackground(background string) map[string]string {
parts := splitBackground(background)
result := make(map[string]string)
// Default component properties
result["background-color"] = ""
result["background-image"] = "none"
result["background-repeat"] = "repeat"
result["background-position"] = "0% 0%"
result["background-size"] = "auto"
result["background-attachment"] = "scroll"
result["background-origin"] = "padding-box"
result["background-clip"] = "border-box"
for _, part := range parts {
switch {
// Handle background-image (assuming url format)
case strings.HasPrefix(part, "url("):
result["background-image"] = part
// Handle background-repeat (no-repeat, repeat-x, repeat-y)
case part == "no-repeat" || part == "repeat" || part == "repeat-x" || part == "repeat-y":
result["background-repeat"] = part
// Handle background-attachment (scroll or fixed)
case part == "scroll" || part == "fixed":
result["background-attachment"] = part
// Handle background-position (percentage or predefined values)
case strings.Contains(part, "%") || isPosition(part):
result["background-position"] = part
// Handle background-size (contain, cover, or specific size)
case part == "contain" || part == "cover" || strings.Contains(part, "px") || strings.Contains(part, "%"):
result["background-size"] = part
// Handle background-origin (border-box, padding-box, content-box)
case part == "border-box" || part == "padding-box" || part == "content-box":
result["background-origin"] = part
result["background-clip"] = part // background-clip defaults to the same as background-origin
// Handle background-color (rgb, rgba, hsl, hsla)
case isColorFunction(part):
result["background-color"] = part
// Handle background-color for basic colors or unknown values
default:
result["background-color"] = part
}
}
return result
}
// splitBackground splits background properties while preserving functions like rgb(), rgba(), hsl(), etc.
func splitBackground(background string) []string {
var result []string
var current strings.Builder
parenDepth := 0
inWord := false
for _, char := range background {
// Track parentheses depth
if char == '(' {
parenDepth++
current.WriteRune(char)
inWord = true
continue
}
if char == ')' {
parenDepth--
current.WriteRune(char)
inWord = true
continue
}
// Handle spaces - they're separators only when not inside parentheses
if char == ' ' || char == '\t' {
if parenDepth > 0 {
// Inside parentheses, preserve the space
current.WriteRune(char)
} else if inWord {
// End of a word, add to results
result = append(result, current.String())
current.Reset()
inWord = false
}
continue
}
// Any other character
current.WriteRune(char)
inWord = true
}
// Add the last part if there is one
if current.Len() > 0 {
result = append(result, current.String())
}
return result
}
// Helper to check if a string is a valid CSS color function (e.g., rgb(), rgba(), hsl(), hsla())
func isColorFunction(value string) bool {
// Check for rgb(), rgba(), hsl(), or hsla() functions
return strings.HasPrefix(value, "rgb(") ||
strings.HasPrefix(value, "rgba(") ||
strings.HasPrefix(value, "hsl(") ||
strings.HasPrefix(value, "hsla(")
}
// Helper to check if a string is a valid background position
func isPosition(value string) bool {
positions := []string{"left", "right", "top", "bottom", "center"}
for _, pos := range positions {
if value == pos {
return true
}
}
return false
}
type FlexProperties struct {
FlexGrow string
FlexShrink string
FlexBasis string
}
func parseFlex(flex string) FlexProperties {
parts := strings.Fields(flex)
prop := FlexProperties{
FlexGrow: "1", // default value
FlexShrink: "1", // default value
FlexBasis: "0%", // default value
}
switch len(parts) {
case 1:
if strings.HasSuffix(parts[0], "%") || strings.HasSuffix(parts[0], "px") || strings.HasSuffix(parts[0], "em") {
prop.FlexBasis = parts[0]
} else if _, err := strconv.ParseFloat(parts[0], 64); err == nil {
prop.FlexGrow = parts[0]
prop.FlexShrink = "1"
prop.FlexBasis = "0%"
} else {
return prop
}
case 2:
prop.FlexGrow = parts[0]
prop.FlexShrink = parts[1]
prop.FlexBasis = "0%"
case 3:
prop.FlexGrow = parts[0]
prop.FlexShrink = parts[1]
prop.FlexBasis = parts[2]
default:
return prop
}
return prop
}
