myst-cli/dist/project/utils.js

Command line tools for MyST

/**
 * Compute the indentation of a YAML line
 *
 * @param line
 */
export function yamlLineIndent(line) {
    const prefix = line.match(/^\s*[^\s#]/)?.[0];
    return prefix ? prefix.length - 1 : undefined;
}
/**
 * Test if line matches YAML section declaration
 *
 * @param name - section name
 * @param line
 *
 **/
function matchesYAMLSection(name, line) {
    // NB the name is not escaped!
    return !!line.match(new RegExp(`^\\s*${name}:\\s*(#.*)?$`));
}
/**
 * Find the start of a YAML section body with a given key.
 *
 * @param name - section name
 * @param indent - indent of parent section
 * @param lines - lines to parse
 * @param index - index of starting line
 *
 * e.g. for the following YAML:
 *   saturn:
 *     best-moons:
 *       - titan
 *       - dione
 *   jupiter:
 *     best-moons:
 *       - io
 *       - europa
 * This function can be used to find the lines bounding the `jupiter`- section, i.e.
 *     best-moons:
 *       - io
 *       - europa
 */
export function findYAMLSection(name, indent, lines, index = 0) {
    let i = index;
    // Find a section with the form
    //   key:
    //     ...
    // Leave `i` at the smallest of:
    //   - the first parent-level indented key (i.e. lesser-indented key)
    //   - the first line after an indented key matching <name>
    //   - `lines.length`
    let foundMatch;
    for (; i < lines.length; i++) {
        const thisIndent = yamlLineIndent(lines[i]);
        if (thisIndent === undefined) {
            continue;
        }
        // Has our indentation finished?
        if (thisIndent < indent) {
            break;
        }
        // If we are too indented, skip
        else if (thisIndent > indent) {
            continue;
        }
        const isMatch = matchesYAMLSection(name, lines[i]);
        if (isMatch) {
            foundMatch = true;
            i++;
            break;
        }
    }
    if (!foundMatch) {
        return undefined;
    }
    // Set start of body
    const start = i;
    // Find section body indent
    let childIndent;
    for (; i < lines.length; i++) {
        childIndent = yamlLineIndent(lines[i]);
        if (childIndent !== undefined) {
            break; // Breaking here stops `i` increment
        }
    }
    // Did we find a child at the same or lower depth to the section title?
    if (childIndent !== undefined) {
        //assert (indent !== undefined)
        if (childIndent <= indent) {
            childIndent = undefined;
        }
    }
    // Otherwise, we have no children!
    if (childIndent === undefined) {
        return { start, stop: start, indent: undefined };
    }
    // Find section stop
    // By having a defined `childIdent`, we know that `i` is valid (== start):
    for (; i < lines.length; i++) {
        const thisIndent = yamlLineIndent(lines[i]);
        if (thisIndent !== undefined && thisIndent < childIndent) {
            break;
        }
    }
    const stop = i;
    return { start, stop, indent: childIndent };
}