Module: Canon::DiffFormatter::Theme

Defined in:
lib/canon/diff_formatter/theme.rb

Overview

Theme definitions for diff display.

Theme is a nested hash structure:

  • diff: removed/added/changed/unchanged/formatting/informative

  • xml: tag/attribute_name/attribute_value/text/comment/cdata

  • html: same as xml

  • structure: line_number/pipe/context

  • visualization: space/tab/newline/nbsp

  • display_mode: :separate/:inline/:mixed

Each styled element has: color, bg, bold, underline, strikethrough, italic

Defined Under Namespace

Classes: Resolver, ThemeInheritance, ValidationResult

Constant Summary collapse

VALID_COLORS =

Valid ANSI color values (standard 16 + common extended colors) Standard: 8 colors + 8 bright variants Extended: light_ variants (for backgrounds), amber (retro terminal)

%i[
  default black red green yellow blue magenta cyan white
  bright_black bright_red bright_green bright_yellow bright_blue bright_magenta bright_cyan bright_white
  light_red light_green light_blue light_cyan light_magenta light_yellow light_black light_white
  amber
].freeze
VALID_DISPLAY_MODES =

Valid display modes

%i[separate inline mixed].freeze
STYLING_PROPERTIES =

Base properties for any styled element

%i[color bg bold underline strikethrough
italic].freeze
LIGHT =

LIGHT THEME - Light terminal backgrounds, professional use

{
  name: "Light",
  description: "Light terminal backgrounds - professional, high contrast",

  diff: {
    removed: {
      marker: { color: :red, bg: :light_red, bold: false },
      content: { color: :red, bg: nil, bold: false, underline: false,
                 strikethrough: true },
    },
    added: {
      marker: { color: :green, bg: :light_green, bold: false },
      content: { color: :green, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    changed: {
      marker: { color: :bright_red, bg: nil, bold: true },
      content_old: { color: :bright_red,   bg: nil, bold: true,
                     underline: false, strikethrough: true },
      content_new: { color: :bright_green, bg: nil, bold: true,
                     underline: true, strikethrough: false },
    },
    unchanged: {
      content: { color: :default, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    formatting: {
      marker: { color: :bright_blue, bg: nil, bold: false },
      content: { color: :bright_blue, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
    informative: {
      marker: { color: :bright_magenta, bg: nil, bold: false },
      content: { color: :bright_magenta, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
  },

  xml: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :magenta, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  html: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :magenta, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  structure: {
    line_number: { color: :black },
    pipe: { color: :black },
    context: { color: :default },
  },

  visualization: {
    space: "░",
    tab: "→",
    newline: "",
    nbsp: "␣",
  },

  display_mode: :separate,
}.freeze
DARK =

DARK THEME - Dark terminal backgrounds, developer favorite

{
  name: "Dark",
  description: "Dark terminal backgrounds - saturated colors, no backgrounds",

  diff: {
    removed: {
      marker: { color: :red, bg: nil, bold: false },
      content: { color: :red, bg: nil, bold: false, underline: false,
                 strikethrough: true },
    },
    added: {
      marker: { color: :green, bg: nil, bold: false },
      content: { color: :green,       bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
    changed: {
      marker: { color: :yellow,       bg: nil, bold: true },
      content_old: { color: :bright_red,   bg: nil, bold: false,
                     underline: false, strikethrough: true },
      content_new: { color: :bright_green, bg: nil, bold: false,
                     underline: true, strikethrough: false },
    },
    unchanged: {
      content: { color: :default, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    formatting: {
      marker: { color: :bright_blue, bg: nil, bold: false },
      content: { color: :bright_blue, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
    informative: {
      marker: { color: :cyan, bg: nil, bold: false },
      content: { color: :cyan, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
  },

  xml: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :cyan, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  html: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :cyan, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  structure: {
    line_number: { color: :white },
    pipe: { color: :white },
    context: { color: :default },
  },

  visualization: {
    space: "░",
    tab: "→",
    newline: "",
    nbsp: "␣",
  },

  display_mode: :separate,
}.freeze
RETRO =

RETRO THEME - Amber CRT, low blue light, accessibility

{
  name: "Retro",
  description: "Amber CRT phosphor - monochromatic amber, low blue light, high accessibility",

  diff: {
    removed: {
      # Bright amber on amber background = inverse video, highest emphasis
      marker: { color: :bright_yellow, bg: :yellow, bold: true },
      content: { color: :bright_yellow, bg: :yellow, bold: true,
                 underline: false, strikethrough: false },
    },
    added: {
      # Bright white = less emphasis than removed, but distinct from normal text
      marker: { color: :bright_white, bg: nil, bold: true },
      content: { color: :bright_white, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
    changed: {
      marker: { color: :bright_yellow, bg: :yellow, bold: true },
      content_old: { color: :bright_yellow, bg: :yellow, bold: true,
                     underline: false, strikethrough: true },
      content_new: { color: :bright_white, bg: nil, bold: false,
                     underline: true, strikethrough: false },
    },
    unchanged: {
      content: { color: :yellow, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    formatting: {
      # Dimmer amber + strikethrough = clearly different from normal text
      marker: { color: :yellow, bg: nil, bold: false,
                strikethrough: true },
      content: { color: :yellow, bg: nil, bold: false, underline: false,
                 strikethrough: true },
    },
    informative: {
      # Bright amber + underline = distinct from formatting and normal
      marker: { color: :bright_yellow, bg: nil, bold: true,
                underline: true },
      content: { color: :bright_yellow, bg: nil, bold: true,
                 underline: true, strikethrough: false },
    },
  },

  xml: {
    # Amber monochrome for all XML elements
    tag: { color: :bright_yellow, bg: nil, bold: true, italic: false },
    attribute_name: { color: :bright_yellow, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :bright_yellow, bg: nil, bold: false,
                       italic: false },
    text: { color: :yellow, bg: nil, bold: false, italic: false },
    comment: { color: :yellow, bg: nil, bold: false, italic: true },
    cdata: { color: :bright_yellow, bg: nil, bold: false, italic: false },
  },

  html: {
    tag: { color: :bright_yellow, bg: nil, bold: true, italic: false },
    attribute_name: { color: :bright_yellow, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :bright_yellow, bg: nil, bold: false,
                       italic: false },
    text: { color: :yellow, bg: nil, bold: false, italic: false },
    comment: { color: :yellow, bg: nil, bold: false, italic: true },
    cdata: { color: :bright_yellow, bg: nil, bold: false, italic: false },
  },

  structure: {
    line_number: { color: :yellow },
    pipe: { color: :yellow },
    context: { color: :yellow },
  },

  visualization: {
    space: "░",
    tab: "→",
    newline: "",
    nbsp: "␣",
  },

  display_mode: :separate,
}.freeze
CLAUDE =

CLAUDE THEME - Claude Code diff style, high contrast HUD

{
  name: "Claude",
  description: "Claude Code diff style - red/green backgrounds, maximum visual pop",

  diff: {
    removed: {
      # Red background + white text = immediate visual pop
      marker: { color: :white, bg: :red, bold: true },
      content: { color: :white, bg: :red, bold: false, underline: false,
                 strikethrough: false },
    },
    added: {
      # Green background + white text (black invisible on dark terminals)
      marker: { color: :white, bg: :green, bold: true },
      content: { color: :white, bg: :green, bold: false,
                 underline: false, strikethrough: false },
    },
    changed: {
      marker: { color: :white, bg: :magenta, bold: true },
      content_old: { color: :bright_red,   bg: nil, bold: false,
                     underline: false, strikethrough: true },
      content_new: { color: :bright_green, bg: nil, bold: false,
                     underline: true, strikethrough: false },
    },
    unchanged: {
      content: { color: :default, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    formatting: {
      marker: { color: :yellow, bg: nil, bold: false },
      content: { color: :yellow, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    informative: {
      marker: { color: :bright_cyan, bg: nil, bold: false },
      content: { color: :bright_cyan, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
  },

  xml: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :cyan, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  html: {
    tag: { color: :bright_blue, bg: nil, bold: true, italic: false },
    attribute_name: { color: :magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :cyan, bg: nil, bold: false, italic: true },
    cdata: { color: :yellow, bg: nil, bold: false, italic: false },
  },

  structure: {
    line_number: { color: :yellow },
    pipe: { color: :yellow },
    context: { color: :default },
  },

  visualization: {
    space: "░",
    tab: "→",
    newline: "",
    nbsp: "␣",
  },

  display_mode: :separate,
}.freeze
CYBERPUNK =

CYBERPUNK THEME - Neon on black, high contrast, futuristic

{
  name: "Cyberpunk",
  description: "Neon on black - high contrast, futuristic, electric",

  diff: {
    removed: {
      # Hot pink/magenta neon for deletions
      marker: { color: :bright_magenta, bg: nil, bold: true },
      content: { color: :bright_magenta, bg: nil, bold: true,
                 underline: false, strikethrough: true },
    },
    added: {
      # Electric cyan neon for additions
      marker: { color: :bright_cyan, bg: nil, bold: true },
      content: { color: :bright_cyan, bg: nil, bold: true,
                 underline: false, strikethrough: false },
    },
    changed: {
      # Yellow warning neon for change markers
      marker: { color: :bright_yellow, bg: nil, bold: true },
      content_old: { color: :bright_magenta, bg: nil, bold: false,
                     underline: false, strikethrough: true },
      content_new: { color: :bright_cyan,    bg: nil, bold: false,
                     underline: true, strikethrough: false },
    },
    unchanged: {
      content: { color: :default, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    formatting: {
      # Dim green for low-priority formatting
      marker: { color: :green, bg: nil, bold: false },
      content: { color: :green, bg: nil, bold: false, underline: false,
                 strikethrough: false },
    },
    informative: {
      # Bright yellow neon for informative
      marker: { color: :bright_yellow, bg: nil, bold: true },
      content: { color: :bright_yellow, bg: nil, bold: false,
                 underline: false, strikethrough: false },
    },
  },

  xml: {
    # Tags in bright cyan, attributes in hot magenta
    tag: { color: :bright_cyan, bg: nil, bold: true, italic: false },
    attribute_name: { color: :bright_magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :bright_green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :green, bg: nil, bold: false, italic: true },
    cdata: { color: :bright_yellow, bg: nil, bold: false, italic: false },
  },

  html: {
    tag: { color: :bright_cyan, bg: nil, bold: true, italic: false },
    attribute_name: { color: :bright_magenta, bg: nil, bold: false,
                      italic: false },
    attribute_value: { color: :bright_green, bg: nil, bold: false,
                       italic: false },
    text: { color: :default, bg: nil, bold: false, italic: false },
    comment: { color: :green, bg: nil, bold: false, italic: true },
    cdata: { color: :bright_yellow, bg: nil, bold: false, italic: false },
  },

  structure: {
    line_number: { color: :bright_cyan },
    pipe: { color: :bright_cyan },
    context: { color: :default },
  },

  visualization: {
    space: "░",
    tab: "→",
    newline: "",
    nbsp: "␣",
  },

  display_mode: :separate,
}.freeze
THEMES =

Registry of all themes

{
  light: LIGHT,
  dark: DARK,
  retro: RETRO,
  claude: CLAUDE,
  cyberpunk: CYBERPUNK,
}.freeze

Class Method Summary collapse

Class Method Details

.[](name) ⇒ Object 



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# File 'lib/canon/diff_formatter/theme.rb', line 614

def self.[](name)
  theme = THEMES[name] || raise(ArgumentError,
                                "Unknown theme: #{name}. Valid: #{THEMES.keys}")
  # Return a deep copy to prevent mutation of theme constants
  deep_dup(theme)
end

.deep_dup(obj) ⇒ Hash

Get a theme by name Deep copy a value, handling nested hashes and arrays

Parameters:

  • name (Symbol) —

    Theme name

Returns:

  • (Hash) —

    Theme hash

Raises:

  • (ArgumentError) —

    if theme not found



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# File 'lib/canon/diff_formatter/theme.rb', line 597

def self.deep_dup(obj)
  case obj
  when Hash
    obj.transform_values { |v| deep_dup(v) }
  when Array
    obj.map { |v| deep_dup(v) }
  when String, Symbol, Numeric, TrueClass, FalseClass, NilClass
    obj
  else
    begin
      obj.dup
    rescue StandardError
      obj
    end
  end
end

.include?(name) ⇒ Boolean

Check if theme name exists

Parameters:

  • name (Symbol)

Returns:

  • (Boolean) 


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# File 'lib/canon/diff_formatter/theme.rb', line 630

def self.include?(name)
  THEMES.key?(name)
end

.inherit_from(base_name) ⇒ ThemeInheritance

Create a new theme by inheriting from a base theme and merging overrides

Parameters:

  • base_name (Symbol) —

    Name of base theme (:light, :dark, :retro, :claude)

Returns:



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# File 'lib/canon/diff_formatter/theme.rb', line 460

def self.inherit_from(base_name)
  ThemeInheritance.new(base_name)
end

.names ⇒ Array<Symbol>

List available theme names

Returns:

  • (Array<Symbol>) 


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# File 'lib/canon/diff_formatter/theme.rb', line 623

def self.names
  THEMES.keys
end

.resolver(config = nil) ⇒ Object

Singleton instance for convenience



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# File 'lib/canon/diff_formatter/theme.rb', line 859

def self.resolver(config = nil)
  Resolver.new(config)
end

.validate(theme) ⇒ ValidationResult

Validate a theme hash has all required keys and valid values

Parameters:

  • theme (Hash) —

    Theme hash to validate

Returns:



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# File 'lib/canon/diff_formatter/theme.rb', line 527

def self.validate(theme)
  missing_keys = []
  extra_keys = []
  invalid_values = []

  # Check top-level keys
  required_toplevel = %i[name description diff xml html structure
                         visualization display_mode]
  required_toplevel.each do |key|
    missing_keys << "top-level.#{key}" unless theme.key?(key)
  end

  # Validate diff section
  if theme[:diff]
    validate_diff_section(theme[:diff], missing_keys, extra_keys,
                          invalid_values)
  end

  # Validate xml section
  if theme[:xml]
    validate_xml_section(theme[:xml], missing_keys, extra_keys,
                         invalid_values)
  end

  # Validate html section
  if theme[:html]
    validate_xml_section(theme[:html], missing_keys, extra_keys,
                         invalid_values)
  end

  # Validate structure
  if theme[:structure]
    validate_structure_section(theme[:structure], missing_keys,
                               extra_keys, invalid_values)
  end

  # Validate visualization
  if theme[:visualization]
    validate_visualization_section(theme[:visualization], missing_keys,
                                   extra_keys, invalid_values)
  end

  # Validate display_mode
  if theme[:display_mode]
    unless VALID_DISPLAY_MODES.include?(theme[:display_mode])
      invalid_values << "display_mode must be one of #{VALID_DISPLAY_MODES}, got #{theme[:display_mode]}"
    end
  else
    missing_keys << "display_mode"
  end

  ValidationResult.new(
    valid: missing_keys.empty? && extra_keys.empty? && invalid_values.empty?,
    missing_keys: missing_keys,
    extra_keys: extra_keys,
    invalid_values: invalid_values,
  )
end

.validate_all ⇒ Hash{Symbol => ValidationResult}

Validate all predefined themes

Returns:



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# File 'lib/canon/diff_formatter/theme.rb', line 588

def self.validate_all
  THEMES.transform_values { |theme| validate(theme) }
end