7.3 Structures And Processing

(require scribble/core)

A document is represented as a part, as described in Parts. This representation is intended to independent of its eventual rendering, and it is intended to be immutable; rendering extensions and specific data in a document can collude arbitrarily, however.

A document is processed in three passes. The first pass is the collect pass, which globally collects information in the document, such as targets for hyperlinking. The second pass is the resolve pass, which matches hyperlink references with targets and expands delayed elements (where the expansion should not contribute new hyperlink targets). The final pass is the render pass, which generates the resulting document. None of the passes mutate the document, but instead collect information in side collect-info and resolve-info tables.

7.3.1 Parts

A part is an instance of part; among other things, it has a title content, an initial flow, and a list of subsection parts. There is no difference between a part and a full document; a particular source module just as easily defines a subsection (incorporated via include-section) as a document.

A flow is a list of blocks.

A block is either a table, an itemization, a nested flow, a paragraph, a compound paragraph, or a delayed block.

• A table is an instance of table; it has a list of list of blocks corresponding to table cells.

• A itemization is an instance of itemization; it has a list of flows.

• A nested flow is an instance of nested-flow; it has a flow that is typeset as sub-flow.

• A paragraph is an instance of paragraph; it has a content:

  • An content can be a string, one of a few symbols, an instance of element (possibly link-element, etc.), a multiarg-element, a part-relative element, a delayed element, or a list of content.

    • A string is included in the result document verbatim, except for space, and unless the content’s enclosing style is 'hspace. In a style other than 'hspace, consecutive spaces in the output may be collapsed togther or replaced with a line break. In the style 'hspace, all text is converted to uncollapsable spaces that cannot be broken across lines.

    • A symbol content is either 'mdash, 'ndash, 'ldquo, 'lsquo, 'rsquo, 'larr, 'rarr, or 'prime; it is rendered as the corresponding HTML entity (even for Latex output).

    • An instance of element has a content plus a style. The style’s interpretation depends on the renderer, but it can be one of a few special symbols (such as 'bold) that are recognized by all renderers.

    • An instance of link-element has a tag for the target of the link.

    • An instance of target-element has a tag to be referenced by link-elements. An instance of the subtype toc-target-element is treated like a kind of section label, to be shown in the “on this page” table for HTML output.

    • An instance of index-element has a tag (as a target), a list of strings for the keywords (for sorting and search), and a list of contents to appear in the end-of-document index.

    • An instance of image-element incorporates an image from a file into the rendered document.

    • An instance of multiarg-element combines a style with a list of content, where the style corresponds to a rendered command that takes multiple arguments.

    • An instance of collect-element has a procedure that is called in the collect pass of document processing to record information used by later passes.

    • A part-relative element is an instance of part-relative-element, which has a procedure that is called in the collect pass of document processing to obtain content. When the part-relative element’s procedure is called, collected information is not yet available, but information about the enclosing parts is available.

    • A delayed element is an instance of delayed-element, which has a procedure that is called in the resolve pass of document processing to obtain content.

    • An instance of render-element has a procedure that is called in the render pass of document processing.

• A compound paragraph is an instance of compound-paragraph; like blockquote, it has list of blocks, but the blocks are typeset as a single paragraph (e.g., no indentation after the first block) instead of inset.

• A delayed block is an instance of delayed-block, which has a procedure that is called in the resolve pass of document processing to obtain a block.

7.3.2 Tags

A tag is a list containing a symbol and either a string, a generated-tag instance, or an arbitrary list. The symbol effectively identifies the type of the tag, such as 'part for a tag that links to a part, or 'def for a Racket function definition. The symbol also effectively determines the interpretation of the second half of the tag.

A part can have a tag prefix, which is effectively added onto the second item within each tag whose first item is 'part or 'tech. The prefix is added to a string value by creating a list containing the prefix and string, and it is added to a list value using cons; a prefix is not added to a generated-tag instance. The prefix is used for reference outside the part, including the use of tags in the part’s tags field. Typically, a document’s main part has a tag prefix that applies to the whole document; references to sections and defined terms within the document from other documents must include the prefix, while references within the same document omit the prefix. Part prefixes can be used within a document as well, to help disambiguate references within the document.

Some procedures accept a “tag” that is just the string part of the full tag, where the symbol part is supplied automatically. For example, section and secref both accept a string “tag”, where 'part is implicit.

7.3.3 Styles

A style combines a style name with a list of style properties in a style structure. A style name is either a string, symbol, of #f. A style property can be anything, including a symbol a structure such as color-property.

A style has a single style name, because the name typically corresponds to a configurable instruction to a renderer. For example, with Latex output, a string style name corresponds to a Latex command or environment. For more information on how string style names interact with configuration of a renderer, see Extending and Configuring Scribble Output. Symbolic style names, meanwhile, provide a simple layer of abstraction between the renderer and documents for widely supported style; for example, the 'italic style name is supported by all renderers.

Style properties within a style compose with style names and other properties. Again, symbols are often used for properties that are directly supported by renderers. For example, 'unnumbered style property for a part renders the part without a section number. Many properties are renderer-specific, such as a hover-property structure that associates text with an element to be shown in an HTML display when the mouse hovers over the text.

7.3.4 Collected and Resolved Information

The collect pass, resolve pass, and render pass processing steps all produce information that is specific to a rendering mode. Concretely, the operations are all represented as methods on a render% object.

The result of the collect method is a collect-info instance. This result is provided back as an argument to the resolve method, which produces a resolve-info value that encapsulates the results from both iterations. The resolve-info value is provided back to the resolve method for final rendering.

Optionally, before the resolve method is called, serialized information from other documents can be folded into the collect-info instance via the deserialize-info method. Other methods provide serialized information out of the collected and resolved records.

During the collect pass, the procedure associated with a collect-element instance can register information with collect-put!.

During the resolve pass, collected information for a part can be extracted with part-collected-info, which includes a part’s number and its parent part (or #f). More generally, the resolve-get method looks up information previously collected. This resolve-time information is normally obtained by the procedure associated with a delayed block or delayed element.

The resolve-get information accepts both a part and a resolve-info argument. The part argument enables searching for information in each enclosing part before sibling parts.

7.3.5 Structure Reference

The tags indicates a list of tags that each link to the section.

The title-content field holds the part’s title, if any.

For the style field, the currently recognized symbolic style names are as follows:

• 'index – The part represents an index.

The recognized style properties are as follows:

• 'unnumbered – A section number is computed for an unnumbered section during the collect pass, but the number is not rendered.

• 'toc – Sub-parts of the part are rendered on separate pages for multi-page HTML mode.

• 'non-toc – Initial sub-parts of the part are not rendered on separate pages for multi-page HTML mode; this style applies only to the main part.

• 'reveal – Shows sub-parts when this part is displayed in a table-of-contents panel in HTML output (which normally shows only the top-level sections).

• 'hidden – The part title is not shown in rendered HTML output.

• 'quiet – In HTML output and most other output modes, hides entries for sub-parts of this part in a table-of-contents or local-table-of-contents listing except when those sub-parts are top-level entries in the listing.

• 'no-toc – As a style for the main part of a document, causes the HTML output to not include a margin box for the main table of contents; the “on this page” box that contains toc-element and toc-target-element links (and that only includes an “on this page” label for multi-page documents) takes on the location and color of the main table of contents, instead.

• document-version structure – A version number for this part and its sub-parts (except as overridden). When it is not "" may be used when rendering a document; at a minimum, a non-"" version is rendered when it is attached to a part representing the whole document. The default version for a document is (version).

• body-id structure – Generated HTML uses the given string id attribute of the body tag; this style can be set separately for parts that start different HTML pages, otherwise it is effectively inherited by sub-parts; the default is "scribble-racket-lang.org", but setup-plt installs "doc-racket-lang.org" as the id for any document that it builds.

The to-collect field contains content that is inspected during the collect pass, but ignored in later passes (i.e., it doesn’t directly contribute to the output).

The blocks field contains the part’s initial flow (before sub-parts).

The parts field contains sub-parts.

For the style field, a string style name corresponds to a CSS class for HTML output or a macro for Latex output (see Implementing Styles). The following symbolic style names are recognized:

• 'author – Typeset as the author of a document. Such paragraphs normally should appear only in the initial flow of a part for a document, where they are treated specially by the Latex renderer by moving the author information to the title.

The currently recognized style properties are as follows:

• 'omitable – When a table cell contains a single omitable-paragraph, then when rendering to HTML, no p tag wraps the cell content.

• 'div – Generates <div> HTML output instead of <p>.

• attributes structure – Provides additional HTML attributes for the <p> or <div> tag.

• body-id structure – For HTML, uses the given string as an id attribute of the <p> or <div> tag.

• 'never-indents – For Latex and compound paragraphs; see compound-paragraph.

Within style, a string style name corresponds to a CSS class for HTML output or an environment for Latex output (see Implementing Styles). The following symbolic style names are also recognized:

• 'boxed – Renders as a definition.

• 'centered – Centers HTML output horizontally.

The following style properties are currently recognized:

• table-columns structure – Provides column-specific styles, but only if a table-cells structure is not included as a style property.

• table-cells structure – Provides cell-specific styles.

• attributes structure – Provides additional HTML attributes for the <table> tag.

• body-id structure – For HTML, uses the given string as an id attribute of the <table> tag.

• 'aux – For HTML, include the table in the table-of-contents display for the enclosing part.

• 'never-indents – For Latex and compound paragraphs; see compound-paragraph.

For Latex output, a paragraph as a cell value is not automatically line-wrapped, unless a vertical alignment is specified for the cell through a table-cells or table-columns style property. To get a line-wrapped paragraph, use a compound-paragraph or use an element with a string style and define a corresponding Latex macro in terms of parbox. For Latex output of blocks in the flow that are nested-flows, itemizations, compound-paragraphs, or delayed-blocks, the block is wrapped with minipage using linewidth divided by the column count as the width.

In style, a string style name corresponds to a CSS class for HTML output or a macro for Latex output (see Implementing Styles). In addition, the following symbolic style names are recognized:

• 'compact – Reduces space between items.

• 'ordered – Generates <ol> HTML output instead of <ul> or an Latex enumeration instead of an itemization.

The following style properties are currently recognized:

• attributes structure – Provides additional HTML attributes for the <ul> or <ol> tag.

• body-id structure – For HTML, uses the given string as an id attribute of the <ul> or <ol> tag.

• 'never-indents – For Latex and compound paragraphs; see compound-paragraph.

In style, the "style name" is normally a string that corresponds to a CSS class for HTML blockquote output or a Latex environment (see Implementing Styles). The following symbolic style names are recognized:

• 'inset – Insets the nested flow relative to surrounding text.

The following style properties are currently recognized:

• 'command – For Latex output, a string style name is used as a command name instead of an environment name.

• attributes structure – Provides additional HTML attributes for the <blockquote> tag.

• body-id structure – For HTML, uses the given string as an id attribute of the <blockquote> tag.

• 'never-indents – For Latex and compound paragraphs; see compound-paragraph.

For HTML, a paragraph block in blocks is rendered without a <p> tag, unless the paragraph has a style with a non-#f style name. For Latex, each block in blocks is rendered with a preceding \noindent, unless the block has the 'never-indents property (checking recursively in a nested-flow or compound-paragraph if the nested-flow or compound-paragraph itself has no 'never-indents property).

The style field of a compound paragraph is normally a string that corresponds to a CSS class for HTML output or Latex environment for Latex output (see Implementing Styles). The following style properties are currently recognized:

• 'command – For Latex output, a string style name is used as a command name instead of an environment name.

• attributes structure – Provides additional HTML attributes for the <p> tag.

• body-id structure – For HTML, uses the given string as an id attribute of the <p> tag.

• 'never-indents – For Latex within another compound paragraph; see above.

The style field can be a style structure, but it can also be just a style name.

In style, a string style name corresponds to a CSS class for HTML output and a macro name for Latex output (see Implementing Styles). The following symbolic style names are recognized:

• 'tt, 'italic, 'bold, 'sf, 'url, 'subscript, 'superscript, 'smaller, 'larger – Basic styles recognized by all renders.

• 'hspace – Renders its content as monospace blanks.

• 'newline – Renders a line break independent of the content.

The following style properties are currently recognized:

• target-url structure – Generates a hyperlink.

• url-anchor structure – For HTML, inserts a hyperlink target before content.

• color-property structure – Applies a color to the text of content.

• background-color-property structure – Applies a color to the background of content.

• attributes structure – Provides additional HTML attributes for a <span> tag.

• hover-property structure – For HTML, adds a text label to the content to be shown when the mouse hovers over it.

• script-property structure – For HTML, supplies a script alternative to content.

• body-id structure – For HTML uses the given string as an id attribute of the span tag.

• 'aux – Intended for use in titles, where the auxiliary part of the title can be omitted in hyperlinks. See, for example, secref.

• 'tt-chars – For Latex output, when the style name is a string, render the element’s content with escapes suitable for Latex tt mode.

• 'exact-chars – For Latex output, when the style name is a string, render the elements content exactly (without escapes).

For each string in suffixes, if the rendered works with the corresponding suffix, the suffix is added to path and used if the resulting path refers to a file that exists. The order in suffixes determines the order in which suffixes are tried. The HTML renderer supports ".png" and ".gif", while the Latex renderer supports ".png", ".pdf", and ".ps" (but rendering Latex output to PDF will not work with ".ps" files, while rendering to Latex DVI output works only with ".ps" files). If suffixes is empty or if none of the suffixes lead to files that exist, path is used as-is.

The scale field scales the image in its rendered form.

When tag is a part tag and the content of the element is null, then the hyperlink uses the target part’s number and/or title as the content. In that case, if the section number is preceded by a word, the word starts in uppercase if the element’s style includes a 'uppercase property.

The entry-seq list must have the same length as plain-seq. It provides the form of each key to render in the final document.

The desc field provides additional information about the index entry as supplied by the entry creator. For example, a reference to a procedure binding can be recognized when desc is an instance of procedure-index-desc. See scribble/manual-struct for other typical types of desc values.

See also index.

The sizer field is a procedure that produces a substitute content for the delayed element for the purposes of determining the delayed element’s width (see element-width).

The plain field is a procedure that produces a substitute content when needed before the collect pass, such as when element->string is used before the collect pass.

The resolve function can call collect-info-parents to obtain a list of parts that enclose the element, starting with the nearest enclosing section. Functions like part-collected-info and collected-info-number can extract information like the part number.

Unlike delayed-element or part-relative-element, the element remains intact (i.e., it is not replaced) by either the collect pass or resolve pass.

If a render-element instance is serialized (such as when saving collected info), it is reduced to a element instance.

If a cell style has a string name, it is used as an HTML class for the <td> tag or as a Latex command name.

The following symbols are recognized as cell-style properties:

• 'left – Left-align the cell content.

• 'right – Right-align the cell content top baselines.

• 'center – Center the cell content horizontally.

• 'top – Top-align the cell content.

• 'baseline – Align the cell content top baselines.

• 'bottom – bottom-align the cell content.

• 'vcenter – Center the cell content vertically.

In addition, for HTML output, attributes structures as style properties can add arbitrary attributes to a cell’s <td> tag.

If p and info arguments are not supplied, then a pre-“collect” substitute is obtained for delayed elements. Otherwise, the two arguments are used to force the delayed element (if it has not been forced already).

For a list that is an info tag, the interpretation of the second element of the list is effectively determined by the leading symbol, which classifies the key. However, a #f value as the second element has an extra meaning: collected information mapped by such info keys is not propagated out of the part where it is collected; that is, the information is available within the part and its sub-parts, but not in ancestor or sibling parts.

Note that every tag is an info key.

The result is #f if the no value for the given key is found. Furthermore, the search failure is recorded for potential consistency reporting, such as when racket setup is used to build documentation.

7.3.6 HTML Style Properties

The path field can be a result of path->main-collects-relative.

7.3.7 Latex Style Properties

The path field can be a result of path->main-collects-relative.

Languages (used with #lang) like scribble/manual and scribble/sigplan add this property to a document to specify appropriate files for Latex rendering.

Languages (used with #lang) like scribble/sigplan add this property to a document to specify appropriate extra files.