Learning to write some pandoc.org filters

convert-headings.js

#!/usr/bin/env node

// Pandoc filter to convert first Para on each OrderedList item into a heading of the appropriate level.
'use strict';

var pandoc = require('pandoc-filter');

var HEADER_LEVELS = {
    'UpperRoman': 1,
    'UpperAlpha': 2,
    'Decimal':    3,
    'LowerAlpha': 4,
    'LowerRoman': 5
}

function strip(type, x) {
    var go = function (key, val) {
        if (key === type) return val;
    }
    return pandoc.walk(x, go, '', {});
}

function create_header(level, list_item) {
    var first_object = list_item[0];
    var content = first_object.c;
    if (first_object.t === 'Header') content = first_object.c[2];
    content = strip('Strong', content);
    list_item[0] = pandoc.Header(level, ["", [], []], content);
}

function action(type,value,format,meta) {
    if (type === 'OrderedList') {
        var current_level = HEADER_LEVELS[value[0][1].t];
        var list_items = value[1];
        list_items.forEach(function(current_item) {
            create_header(current_level, current_item)
        });
        return pandoc.OrderedList(value[0], value[1]);
    }
}

pandoc.stdio(action);

move-inline-linebreak.js

#!/usr/bin/env node

// Pandoc filter to split move LineBreaks outside other Inlines
'use strict';

var pandoc = require('pandoc-filter');

function action(type,value,format,meta) {
    if (type === 'Span') return value[1];
    if (type === 'Strong' || type === 'Emph') {
        var result = [];
        var lb = null;
        value.forEach(function(currentValue, index, array) {
            if (currentValue.t === 'LineBreak') {
                lb = currentValue;
            } else {
                result.push(currentValue)
            }
        })
        if (lb !== null) return [pandoc[type](result), lb];
    }
}

pandoc.stdio(action);

split-paras.js

#!/usr/bin/env node

// Pandoc filter to split Para elements on eack LineBreak
'use strict';

var pandoc = require('pandoc-filter');

function action(type,value,format,meta) {
    if (type === 'Para' || type === 'Plain') {
        var result = [];
        var curr = [];
        value.forEach(function(currentValue, index, array) {
            if (currentValue.t === 'LineBreak') {
                result.push(pandoc.Para(curr));
                curr = []
            } else {
                curr.push(currentValue)
            }
        })
        result.push(pandoc.Para(curr));
        return result;
    }
}

pandoc.stdio(action);