cheat/vendor/github.com/alecthomas/chroma/style.go

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2019-10-27 17:04:31 +01:00
package chroma
import (
"fmt"
"strings"
)
// Trilean value for StyleEntry value inheritance.
type Trilean uint8
// Trilean states.
const (
Pass Trilean = iota
Yes
No
)
func (t Trilean) String() string {
switch t {
case Yes:
return "Yes"
case No:
return "No"
default:
return "Pass"
}
}
// Prefix returns s with "no" as a prefix if Trilean is no.
func (t Trilean) Prefix(s string) string {
if t == Yes {
return s
} else if t == No {
return "no" + s
}
return ""
}
// A StyleEntry in the Style map.
type StyleEntry struct {
// Hex colours.
Colour Colour
Background Colour
Border Colour
Bold Trilean
Italic Trilean
Underline Trilean
NoInherit bool
}
func (s StyleEntry) String() string {
out := []string{}
if s.Bold != Pass {
out = append(out, s.Bold.Prefix("bold"))
}
if s.Italic != Pass {
out = append(out, s.Italic.Prefix("italic"))
}
if s.Underline != Pass {
out = append(out, s.Underline.Prefix("underline"))
}
if s.NoInherit {
out = append(out, "noinherit")
}
if s.Colour.IsSet() {
out = append(out, s.Colour.String())
}
if s.Background.IsSet() {
out = append(out, "bg:"+s.Background.String())
}
if s.Border.IsSet() {
out = append(out, "border:"+s.Border.String())
}
return strings.Join(out, " ")
}
// Sub subtracts e from s where elements match.
func (s StyleEntry) Sub(e StyleEntry) StyleEntry {
out := StyleEntry{}
if e.Colour != s.Colour {
out.Colour = s.Colour
}
if e.Background != s.Background {
out.Background = s.Background
}
if e.Bold != s.Bold {
out.Bold = s.Bold
}
if e.Italic != s.Italic {
out.Italic = s.Italic
}
if e.Underline != s.Underline {
out.Underline = s.Underline
}
if e.Border != s.Border {
out.Border = s.Border
}
return out
}
// Inherit styles from ancestors.
//
// Ancestors should be provided from oldest to newest.
func (s StyleEntry) Inherit(ancestors ...StyleEntry) StyleEntry {
out := s
for i := len(ancestors) - 1; i >= 0; i-- {
if out.NoInherit {
return out
}
ancestor := ancestors[i]
if !out.Colour.IsSet() {
out.Colour = ancestor.Colour
}
if !out.Background.IsSet() {
out.Background = ancestor.Background
}
if !out.Border.IsSet() {
out.Border = ancestor.Border
}
if out.Bold == Pass {
out.Bold = ancestor.Bold
}
if out.Italic == Pass {
out.Italic = ancestor.Italic
}
if out.Underline == Pass {
out.Underline = ancestor.Underline
}
}
return out
}
func (s StyleEntry) IsZero() bool {
return s.Colour == 0 && s.Background == 0 && s.Border == 0 && s.Bold == Pass && s.Italic == Pass &&
s.Underline == Pass && !s.NoInherit
}
// A StyleBuilder is a mutable structure for building styles.
//
// Once built, a Style is immutable.
type StyleBuilder struct {
entries map[TokenType]string
name string
parent *Style
}
func NewStyleBuilder(name string) *StyleBuilder {
return &StyleBuilder{name: name, entries: map[TokenType]string{}}
}
func (s *StyleBuilder) AddAll(entries StyleEntries) *StyleBuilder {
for ttype, entry := range entries {
s.entries[ttype] = entry
}
return s
}
func (s *StyleBuilder) Get(ttype TokenType) StyleEntry {
// This is less than ideal, but it's the price for having to check errors on each Add().
entry, _ := ParseStyleEntry(s.entries[ttype])
return entry.Inherit(s.parent.Get(ttype))
}
// Add an entry to the Style map.
//
// See http://pygments.org/docs/styles/#style-rules for details.
func (s *StyleBuilder) Add(ttype TokenType, entry string) *StyleBuilder { // nolint: gocyclo
s.entries[ttype] = entry
return s
}
func (s *StyleBuilder) AddEntry(ttype TokenType, entry StyleEntry) *StyleBuilder {
s.entries[ttype] = entry.String()
return s
}
func (s *StyleBuilder) Build() (*Style, error) {
style := &Style{
Name: s.name,
entries: map[TokenType]StyleEntry{},
parent: s.parent,
}
for ttype, descriptor := range s.entries {
entry, err := ParseStyleEntry(descriptor)
if err != nil {
return nil, fmt.Errorf("invalid entry for %s: %s", ttype, err)
}
style.entries[ttype] = entry
}
return style, nil
}
// StyleEntries mapping TokenType to colour definition.
type StyleEntries map[TokenType]string
// NewStyle creates a new style definition.
func NewStyle(name string, entries StyleEntries) (*Style, error) {
return NewStyleBuilder(name).AddAll(entries).Build()
}
// MustNewStyle creates a new style or panics.
func MustNewStyle(name string, entries StyleEntries) *Style {
style, err := NewStyle(name, entries)
if err != nil {
panic(err)
}
return style
}
// A Style definition.
//
// See http://pygments.org/docs/styles/ for details. Semantics are intended to be identical.
type Style struct {
Name string
entries map[TokenType]StyleEntry
parent *Style
}
// Types that are styled.
func (s *Style) Types() []TokenType {
dedupe := map[TokenType]bool{}
for tt := range s.entries {
dedupe[tt] = true
}
if s.parent != nil {
for _, tt := range s.parent.Types() {
dedupe[tt] = true
}
}
out := make([]TokenType, 0, len(dedupe))
for tt := range dedupe {
out = append(out, tt)
}
return out
}
// Builder creates a mutable builder from this Style.
//
// The builder can then be safely modified. This is a cheap operation.
func (s *Style) Builder() *StyleBuilder {
return &StyleBuilder{
name: s.Name,
entries: map[TokenType]string{},
parent: s,
}
}
// Has checks if an exact style entry match exists for a token type.
//
// This is distinct from Get() which will merge parent tokens.
func (s *Style) Has(ttype TokenType) bool {
return !s.get(ttype).IsZero() || s.synthesisable(ttype)
}
// Get a style entry. Will try sub-category or category if an exact match is not found, and
// finally return the Background.
func (s *Style) Get(ttype TokenType) StyleEntry {
return s.get(ttype).Inherit(
s.get(Background),
s.get(Text),
s.get(ttype.Category()),
s.get(ttype.SubCategory()))
}
func (s *Style) get(ttype TokenType) StyleEntry {
out := s.entries[ttype]
if out.IsZero() && s.parent != nil {
return s.parent.get(ttype)
}
if out.IsZero() && s.synthesisable(ttype) {
out = s.synthesise(ttype)
}
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return out
}
func (s *Style) synthesise(ttype TokenType) StyleEntry {
bg := s.get(Background)
text := StyleEntry{Colour: bg.Colour}
text.Colour = text.Colour.BrightenOrDarken(0.5)
switch ttype {
// If we don't have a line highlight colour, make one that is 10% brighter/darker than the background.
case LineHighlight:
return StyleEntry{Background: bg.Background.BrightenOrDarken(0.1)}
// If we don't have line numbers, use the text colour but 20% brighter/darker
case LineNumbers, LineNumbersTable:
return text
default:
return StyleEntry{}
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}
}
func (s *Style) synthesisable(ttype TokenType) bool {
return ttype == LineHighlight || ttype == LineNumbers || ttype == LineNumbersTable
}
// ParseStyleEntry parses a Pygments style entry.
func ParseStyleEntry(entry string) (StyleEntry, error) { // nolint: gocyclo
out := StyleEntry{}
parts := strings.Fields(entry)
for _, part := range parts {
switch {
case part == "italic":
out.Italic = Yes
case part == "noitalic":
out.Italic = No
case part == "bold":
out.Bold = Yes
case part == "nobold":
out.Bold = No
case part == "underline":
out.Underline = Yes
case part == "nounderline":
out.Underline = No
case part == "inherit":
out.NoInherit = false
case part == "noinherit":
out.NoInherit = true
case part == "bg:":
out.Background = 0
case strings.HasPrefix(part, "bg:#"):
out.Background = ParseColour(part[3:])
if !out.Background.IsSet() {
return StyleEntry{}, fmt.Errorf("invalid background colour %q", part)
}
case strings.HasPrefix(part, "border:#"):
out.Border = ParseColour(part[7:])
if !out.Border.IsSet() {
return StyleEntry{}, fmt.Errorf("invalid border colour %q", part)
}
case strings.HasPrefix(part, "#"):
out.Colour = ParseColour(part)
if !out.Colour.IsSet() {
return StyleEntry{}, fmt.Errorf("invalid colour %q", part)
}
default:
return StyleEntry{}, fmt.Errorf("unknown style element %q", part)
}
}
return out, nil
}