Renderer Package

This page documents the renderer package (github.com/frostybee/nuri/renderer). Most consumers use the highlighter methods (h.CodeToHTML(), h.CodeToANSI(), etc.), which wrap these functions. Import the renderer package directly when building a custom rendering pipeline or a downstream library like Kazari.

renderer.BuildTree

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func BuildTree(result *ast.TokensResult, opts *ast.CodeToHTMLOptions) *ast.Element

Converts a *TokensResult into an HTML element tree. This is the main HTML construction function called by h.CodeToHTML() between the Tokens and Postprocess transformer hooks.

Single-theme output: The <pre> element gets classes ["nuri", themeName] with inline background-color and color styles.

Multi-theme output: The <pre> element gets classes ["nuri", "nuri-themes", key1, key2, ...] with CSS variables --nuri-{key}-bg and --nuri-{key} for each non-default theme.

The <pre> element always has tabindex="0". Lines are <span class="line"> elements separated by "\n" text nodes. Per-token byte offsets (UTF-8) are accumulated and passed to Transformer.Span as the col parameter.

The function applies all decoration classes (highlighted, focused/dimmed, diff add/diff remove), runs transformer hooks (Span, Line, Code, Pre, Root), and replaces inline styles with hashed class names when opts.ClassMap is non-nil.

Returns: The root *ast.Element, serializable via WriteTo(w io.Writer).

renderer.TokenStyles

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func TokenStyles(tok ast.ThemedToken) map[string]string

Converts a token's resolved style into an inline CSS property map for single-theme mode. Used internally by BuildTree for each <span> element.

Possible keys: "color", "background-color", "font-style", "font-weight", "text-decoration". Returns an empty map if the token has no styling.

renderer.TokenStylesMulti

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func TokenStylesMulti(tok ast.ThemedToken, defaultColor bool) map[string]string

Converts a token's resolved style into a combined CSS property map for multi-theme mode. When defaultColor is true, emits standard inline properties (color, background-color, font properties) for the default theme. For each non-default theme key in tok.ThemeStyles, emits CSS custom properties:

• --nuri-{key} for foreground color
• --nuri-{key}-bg for background color
• --nuri-{key}-font-style, --nuri-{key}-font-weight, --nuri-{key}-text-decoration for font style

renderer.FontStyleCSS

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func FontStyleCSS(fs theme.FontStyle) map[string]string

Translates a theme.FontStyle bitmask into CSS properties.

When both underline and strikethrough are set, text-decoration is "underline line-through".

Returns: nil when fs <= 0 (covers both FontStyleNone and FontStyleNotSet).

renderer.RenderANSI

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func RenderANSI(w io.Writer, result *ast.TokensResult, opts *ast.CodeToANSIOptions) error

Writes ANSI SGR escape sequences to w. Applies foreground color and font style (bold, italic, underline, strikethrough) per token. Resets after each styled token with \033[0m.

opts.ColorDepth controls how hex colors map to ANSI codes:

Tokens without an explicit foreground color fall back to result.FG. Background colors from tokens are not emitted. Lines are separated by "\n" with no trailing newline.

Returns: The first io.Writer error encountered, or nil.

renderer.RenderSVG

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func RenderSVG(w io.Writer, result *ast.TokensResult, opts *ast.CodeToSVGOptions) error

Writes a self-contained SVG document to w. Each line becomes a <text> element; styled tokens become <tspan> children with fill, font-weight, font-style, and text-decoration attributes.

Spaces are replaced with   to preserve whitespace. Tabs are expanded to opts.TabWidth non-breaking spaces. Tokens whose color equals the default foreground omit the fill attribute (inherited from the parent <g>).

SVG-specific options (FontFamily, FontSize, LineHeight, PadX, PadY, CornerRadius, ShowBackground) apply renderer defaults when zero-valued. See Types for the CodeToSVGOptions field table.

Returns: The first write error, or nil.

renderer.RenderPlainText

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func RenderPlainText(w io.Writer, result *ast.TokensResult) error

Writes raw token content to w with no formatting. Lines are joined with "\n". All color, font style, and scope information is ignored.

Returns: The first write error, or nil.