eval

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 Go to latest Published: Mar 29, 2026 License: MIT Imports: 4 Imported by: 0

Documentation

Overview

Package eval provides color math and terminal palette utilities for evaluating widget contrast and theme coherence. This is non-production test tooling — it is not in the hot path.

Package eval provides a graded design report for rendered statusline output. It wires together the color math (color.go), terminal palettes (palette.go), and ANSI parser (parse.go) to score four dimensions of visual quality: contrast, coherence, hierarchy, and adaptability.

Package eval provides tools for inspecting rendered ANSI output from the statusline. Parse() decodes escape sequences into structured segments so downstream code can reason about colors and attributes without dealing with raw escape bytes.

Index

Constants

This section is empty.

Variables

View Source 
var CatppuccinMocha = TerminalPalette{
	Name:      "CatppuccinMocha",
	DefaultFg: RGB{0xcd, 0xd6, 0xf4},
	DefaultBg: RGB{0x1e, 0x1e, 0x2e},
	Colors: [16]RGB{
		{0x45, 0x47, 0x5a},
		{0xf3, 0x8b, 0xa8},
		{0xa6, 0xe3, 0xa1},
		{0xf9, 0xe2, 0xaf},
		{0x89, 0xb4, 0xfa},
		{0xf5, 0xc2, 0xe7},
		{0x94, 0xe2, 0xd5},
		{0xba, 0xc2, 0xde},
		{0x58, 0x5b, 0x70},
		{0xf3, 0x8b, 0xa8},
		{0xa6, 0xe3, 0xa1},
		{0xf9, 0xe2, 0xaf},
		{0x89, 0xb4, 0xfa},
		{0xf5, 0xc2, 0xe7},
		{0x94, 0xe2, 0xd5},
		{0xcd, 0xd6, 0xf4},
	},
}

CatppuccinMocha uses the Catppuccin Mocha color scheme. Source: https://github.com/catppuccin/catppuccin

View Source 
var Dracula = TerminalPalette{
	Name:      "Dracula",
	DefaultFg: RGB{0xf8, 0xf8, 0xf2},
	DefaultBg: RGB{0x28, 0x2a, 0x36},
	Colors: [16]RGB{
		{0x21, 0x22, 0x2c},
		{0xff, 0x55, 0x55},
		{0x50, 0xfa, 0x7b},
		{0xf1, 0xfa, 0x8c},
		{0xbd, 0x93, 0xf9},
		{0xff, 0x79, 0xc6},
		{0x8b, 0xe9, 0xfd},
		{0xf8, 0xf8, 0xf2},
		{0x6a, 0x71, 0x86},
		{0xff, 0x6e, 0x6e},
		{0x69, 0xff, 0x94},
		{0xff, 0xff, 0xa5},
		{0xd6, 0xac, 0xff},
		{0xff, 0x92, 0xdf},
		{0xa4, 0xff, 0xff},
		{0xff, 0xff, 0xff},
	},
}

Dracula uses the Dracula color scheme. Source: https://github.com/dracula/dracula-theme

View Source 
var GruvboxDark = TerminalPalette{
	Name:      "GruvboxDark",
	DefaultFg: RGB{0xeb, 0xdb, 0xb2},
	DefaultBg: RGB{0x28, 0x28, 0x28},
	Colors: [16]RGB{
		{0x28, 0x28, 0x28},
		{0xcc, 0x24, 0x1d},
		{0x98, 0x97, 0x1a},
		{0xd7, 0x99, 0x21},
		{0x45, 0x85, 0x88},
		{0xb1, 0x62, 0x86},
		{0x68, 0x9d, 0x6a},
		{0xa8, 0x99, 0x84},
		{0x92, 0x83, 0x74},
		{0xfb, 0x49, 0x34},
		{0xb8, 0xbb, 0x26},
		{0xfa, 0xbd, 0x2f},
		{0x83, 0xa5, 0x98},
		{0xd3, 0x86, 0x9b},
		{0x8e, 0xc0, 0x7c},
		{0xeb, 0xdb, 0xb2},
	},
}

GruvboxDark uses the Gruvbox dark color scheme by morhetz. Source: https://github.com/morhetz/gruvbox

View Source 
var Nord = TerminalPalette{
	Name:      "Nord",
	DefaultFg: RGB{0xd8, 0xde, 0xe9},
	DefaultBg: RGB{0x2e, 0x34, 0x40},
	Colors: [16]RGB{
		{0x3b, 0x42, 0x52},
		{0xbf, 0x61, 0x6a},
		{0xa3, 0xbe, 0x8c},
		{0xeb, 0xcb, 0x8b},
		{0x81, 0xa1, 0xc1},
		{0xb4, 0x8e, 0xad},
		{0x88, 0xc0, 0xd0},
		{0xe5, 0xe9, 0xf0},
		{0x4c, 0x56, 0x6a},
		{0xbf, 0x61, 0x6a},
		{0xa3, 0xbe, 0x8c},
		{0xeb, 0xcb, 0x8b},
		{0x81, 0xa1, 0xc1},
		{0xb4, 0x8e, 0xad},
		{0x8f, 0xbc, 0xbb},
		{0xec, 0xef, 0xf4},
	},
}

Nord uses the Nord color scheme by Arctic Ice Studio. Source: https://www.nordtheme.com/

View Source 
var SolarizedDark = TerminalPalette{
	Name:      "SolarizedDark",
	DefaultFg: RGB{0x83, 0x94, 0x96},
	DefaultBg: RGB{0x00, 0x2b, 0x36},
	Colors: [16]RGB{
		{0x07, 0x36, 0x42},
		{0xdc, 0x32, 0x2f},
		{0x85, 0x99, 0x00},
		{0xb5, 0x89, 0x00},
		{0x26, 0x8b, 0xd2},
		{0xd3, 0x36, 0x82},
		{0x2a, 0xa1, 0x98},
		{0xee, 0xe8, 0xd5},
		{0x00, 0x2b, 0x36},
		{0xcb, 0x4b, 0x16},
		{0x58, 0x6e, 0x75},
		{0x65, 0x7b, 0x83},
		{0x83, 0x94, 0x96},
		{0x6c, 0x71, 0xc4},
		{0x93, 0xa1, 0xa1},
		{0xfd, 0xf6, 0xe3},
	},
}

SolarizedDark uses Ethan Schoonover's Solarized dark scheme. Source: https://ethanschoonover.com/solarized/

View Source 
var SolarizedLight = TerminalPalette{
	Name:      "SolarizedLight",
	DefaultFg: RGB{0x65, 0x7b, 0x83},
	DefaultBg: RGB{0xfd, 0xf6, 0xe3},
	Colors: [16]RGB{
		{0x07, 0x36, 0x42},
		{0xdc, 0x32, 0x2f},
		{0x85, 0x99, 0x00},
		{0xb5, 0x89, 0x00},
		{0x26, 0x8b, 0xd2},
		{0xd3, 0x36, 0x82},
		{0x2a, 0xa1, 0x98},
		{0xee, 0xe8, 0xd5},
		{0x00, 0x2b, 0x36},
		{0xcb, 0x4b, 0x16},
		{0x58, 0x6e, 0x75},
		{0x65, 0x7b, 0x83},
		{0x83, 0x94, 0x96},
		{0x6c, 0x71, 0xc4},
		{0x93, 0xa1, 0xa1},
		{0xfd, 0xf6, 0xe3},
	},
}

SolarizedLight uses Ethan Schoonover's Solarized light scheme. Source: https://ethanschoonover.com/solarized/

View Source 
var TokyoNight = TerminalPalette{
	Name:      "TokyoNight",
	DefaultFg: RGB{0xc0, 0xca, 0xf5},
	DefaultBg: RGB{0x1a, 0x1b, 0x26},
	Colors: [16]RGB{
		{0x15, 0x16, 0x22},
		{0xf7, 0x76, 0x8e},
		{0x9e, 0xce, 0x6a},
		{0xe0, 0xaf, 0x68},
		{0x7a, 0xa2, 0xf7},
		{0xbb, 0x9a, 0xf7},
		{0x7d, 0xcf, 0xff},
		{0xa9, 0xb1, 0xd6},
		{0x41, 0x44, 0x68},
		{0xf7, 0x76, 0x8e},
		{0x9e, 0xce, 0x6a},
		{0xe0, 0xaf, 0x68},
		{0x7a, 0xa2, 0xf7},
		{0xbb, 0x9a, 0xf7},
		{0x7d, 0xcf, 0xff},
		{0xc0, 0xca, 0xf5},
	},
}

TokyoNight uses the Tokyo Night color scheme by enkia. Source: https://github.com/enkia/tokyo-night-vscode-theme

View Source 
var XtermDefault = TerminalPalette{
	Name:      "XtermDefault",
	DefaultFg: RGB{0xc0, 0xc0, 0xc0},
	DefaultBg: RGB{0x00, 0x00, 0x00},
	Colors: [16]RGB{
		{0x00, 0x00, 0x00},
		{0x80, 0x00, 0x00},
		{0x00, 0x80, 0x00},
		{0x80, 0x80, 0x00},
		{0x00, 0x00, 0x80},
		{0x80, 0x00, 0x80},
		{0x00, 0x80, 0x80},
		{0xc0, 0xc0, 0xc0},
		{0x80, 0x80, 0x80},
		{0xff, 0x00, 0x00},
		{0x00, 0xff, 0x00},
		{0xff, 0xff, 0x00},
		{0x00, 0x00, 0xff},
		{0xff, 0x00, 0xff},
		{0x00, 0xff, 0xff},
		{0xff, 0xff, 0xff},
	},
}

XtermDefault uses the canonical xterm default colors. Fg: Silver (#c0c0c0), Bg: Black (#000000).

Functions

func ContrastRatio 

func ContrastRatio(fg, bg RGB) float64

ContrastRatio returns the WCAG 2.1 contrast ratio between two colors. The result is in the range [1, 21]. A ratio of 21 means maximum contrast (black on white); 1 means no contrast (identical colors).

func FormatReport 

func FormatReport(report Report) string

FormatReport formats a Report as human-readable text suitable for logging or terminal output.

func HueDelta 

func HueDelta(h1, h2 float64) float64

HueDelta returns the shortest arc distance between two hue values in degrees. The result is always in [0, 180].

func RGBToHSL 

func RGBToHSL(c RGB) (h, s, l float64)

RGBToHSL converts an RGB color to HSL (hue, saturation, lightness). Hue is in degrees [0, 360), saturation and lightness are in [0, 1].

func RelativeLuminance 

func RelativeLuminance(c RGB) float64

RelativeLuminance returns the WCAG 2.1 relative luminance of an RGB color. The result is in the range [0, 1], where 0 is black and 1 is white.

Types

type Color 

type Color struct {
	Type  ColorType
	Index int   // valid for ColorANSI16 and ColorXterm256
	R     uint8 // valid for ColorTruecolor
	G     uint8 // valid for ColorTruecolor
	B     uint8 // valid for ColorTruecolor
}

Color holds a resolved terminal color value.

type ColorType 

type ColorType int

ColorType identifies which color space a Color value lives in. 

const (
	// ColorDefault means no explicit color was set (terminal default).
	ColorDefault ColorType = iota
	// ColorANSI16 is one of the 16 standard ANSI colors (indices 0-15).
	ColorANSI16
	// ColorXterm256 is one of the 256 xterm palette colors (indices 0-255).
	ColorXterm256
	// ColorTruecolor is a 24-bit RGB color.
	ColorTruecolor
)

type DimensionResult 

type DimensionResult struct {
	Name     string
	Grade    Grade
	Findings []string
}

DimensionResult holds the outcome of scoring one design dimension.

type Grade 

type Grade string

Grade is a letter grade for a scored dimension. 

const (
	GradeA Grade = "A"
	GradeB Grade = "B"
	GradeC Grade = "C"
	GradeD Grade = "D"
	GradeF Grade = "F"
)

type RGB 

type RGB struct {
	R, G, B uint8
}

RGB holds a 24-bit color as three 8-bit channels.

func Xterm256ToRGB 

func Xterm256ToRGB(index int) RGB

Xterm256ToRGB returns the canonical RGB value for an xterm-256 color index. Indices outside 0-255 are clamped to the valid range.

type Report 

type Report struct {
	Dimensions []DimensionResult
	Overall    Grade
}

Report aggregates all dimension results and an overall grade.

func Evaluate 

func Evaluate(rendered string, mode string) Report

Evaluate parses rendered ANSI output, scores each design dimension, and returns a Report. The mode parameter is accepted for future use but does not currently affect scoring.

type StyledSegment 

type StyledSegment struct {
	Text  string
	Fg    Color
	Bg    Color
	Bold  bool
	Faint bool
}

StyledSegment is a run of visible text with uniform styling.

func Parse 

func Parse(input string) []StyledSegment

Parse walks input, extracts SGR escape sequences, and returns a slice of StyledSegment values. Adjacent segments with identical styling are merged; segments with empty text are dropped.

type TerminalPalette 

type TerminalPalette struct {
	Name      string
	DefaultFg RGB
	DefaultBg RGB
	Colors    [16]RGB
}

TerminalPalette describes a terminal color scheme. Colors[0-7] are the standard ANSI colors, Colors[8-15] are the bright variants.

func AllPalettes 

func AllPalettes() []TerminalPalette

AllPalettes returns all built-in terminal palettes.

Source Files

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