/**
 * Configuration values the engine cannot use as written. The engine never
 * fails on them — it numbers in decimal, sets a font stack in its first
 * family, cuts the columns of a one-and-a-half layout at the nearest width
 * both can take, ignores a heading setting it does not know — but a silent
 * substitution is hard to spot, so every one is reported: on
 * `VDTDocument.configWarnings`, and to any host that asks with
 * {@link collectConfigWarnings}.
 */
import type { PostextConfig, Resource, DocumentMetadata } from './types.js';
import type { ConfigWarning } from './vdt.js';
/**
 * Walk a config for values the engine replaces or leaves out:
 * - an unknown numbering format (lists, page labels, resource counters —
 *   any of their spellings is fine, see `parseNumberFormat`) and a CSS font
 *   stack in a font-family field, in every nested partial config (heading
 *   styles, part list overrides, `htmlViewer.overrides`, design elements);
 * - the `sideColumnPercent` of a one-and-a-half layout that would leave one
 *   of the columns with no width (see `sideColumnPercentUsed`), and the
 *   column count of a `multiple` layout that is no whole number from 3 to
 *   8 — the document's, and every heading style's own `layout`;
 * - a character grid (`cjk.grid`) larger than the page leaves room for;
 * - a key the heading settings or a paragraph style do not have
 *   (`unknownConfigKey`: `headings`, its `balancing` and `levels`,
 *   `headingStyles`, `paragraphStyles`), a top-level key a config does not
 *   have, and a key a design element, its placement or a connector's end
 *   does not have (#1122);
 * - a setting with a value outside its choices (`unknownConfigValue`):
 *   `direction`, the Arabic body text words (`emphasis`, `tashkil`,
 *   `kashida`, `kashidaPatterns`), the composition rules, `toc.groups.head`,
 *   a heading's `numberPosition`, spread footnotes in a horizontal
 *   document, the comics words, `print.standard`, `outputProfile` and
 *   `renderingIntent`, the contrast check, the Canvas gaps
 *   (`canvasViewer`), the `checks.contentInConfig` limits (`maxWords`,
 *   `maxChars`), the line numbers, a resource type's `resetOn` and text
 *   wrap, the code style, tab stops and drop caps; line numbers or text
 *   wrap asked of a vertical document (`lineNumbersUnsupported`,
 *   `wrapUnsupported`);
 * - a `numerals` value that names no digit system (`unknownNumerals`);
 * - page templates and label styles (see `validatePageTemplates`), and a
 *   box style whose `extends` names no style or comes back to itself;
 * - the design texts that hold the book's content instead of placeholders
 *   (`contentInConfig`, #849, tuned by `checks.contentInConfig`);
 * - a design element's point along a side (`anchor.at`) or size edge
 *   (`size.width.edge`…) outside its choices (`unknownConfigValue`, #1055);
 * - a path element's keys, path data, `viewBox` and
 *   `preserveAspectRatio` (#1060);
 * - box shapes (#1059): corner and side keys a box does not have, a label
 *   tab's `position` outside its choices, a joined tab with an `offset`;
 * - a design element's `when` / `unless` that names no attribute, or that
 *   a heading, part or box design would ignore (#1087);
 * - the exercise styles and settings (#1226): keys they do not have, words
 *   outside their choices, numbering styles the engine does not know.
 * Pure.
 */
export declare function collectConfigWarnings(config: PostextConfig | undefined, options?: ConfigWarningOptions): ConfigWarning[];
/** What else the config checks may read. */
export interface ConfigWarningOptions {
    /** The book's resources: an anchor's label `style` is checked against
     *  `labelStyles` (`labelStyleUnknown`). */
    resources?: readonly Resource[];
    /** The document's metadata (its front matter): its `title`, `subtitle`,
     *  `author` and `publisher` are allowed in a design text as if listed in
     *  `checks.contentInConfig.allow`, since a running head often repeats
     *  them. */
    metadata?: DocumentMetadata;
}
/** The literal text a design text prints whatever the document: its
 *  content with every placeholder removed, on one line (#849). */
export declare function designTextLiteral(content: string): string;
/** How the `contentInConfig` check reads one design text: its literal
 *  (placeholders removed), what is left once the allowed phrases are taken
 *  out (`rest`, compared without case), the letters and digits of `rest`,
 *  and whether the text counts as content. */
export interface DesignTextVerdict {
    literal: string;
    rest: string;
    chars: number;
    content: boolean;
}
/** The `contentInConfig` rule of a configuration (#849), as a function of a
 *  design text's `content`: the check's settings and allowed phrases (and
 *  the metadata's) read once. Disabled checks still answer, as if enabled:
 *  the migration of #874 asks what the check would say. Pure. */
export declare function contentInConfigRule(config: PostextConfig | undefined, options?: ConfigWarningOptions): (content: string) => DesignTextVerdict;
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