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var _ = require("underscore");
var ast = require("./ast");
function simplify(nodes) {
return collapse(removeEmpty(nodes));
}
function collapse(nodes) {
var children = [];
nodes.map(collapseNode).forEach(function(child) {
appendChild(children, child);
});
return children;
}
function collapseNode(node) {
return collapsers[node.type](node);
}
var collapsers = {
element: collapseElement,
selfClosingElement: identity,
text: identity,
forceWrite: identity
};
function collapseElement(node) {
return ast.elementWithTag(node.tag, collapse(node.children));
}
function identity(value) {
return value;
}
function appendChild(children, child) {
var lastChild = children[children.length - 1];
if (child.type === "element" && !child.tag.fresh && lastChild && lastChild.type === "element" && child.tag.matchesElement(lastChild.tag)) {
if (child.tag.separator) {
appendChild(lastChild.children, ast.text(child.tag.separator));
}
child.children.forEach(function(grandChild) {
// Mutation is fine since simplifying elements create a copy of the children.
appendChild(lastChild.children, grandChild);
});
} else {
children.push(child);
}
}
function removeEmpty(nodes) {
return flatMap(nodes, function(node) {
return emptiers[node.type](node);
});
}
function flatMap(values, func) {
return _.flatten(_.map(values, func), true);
}
var emptiers = {
element: elementEmptier,
selfClosingElement: neverEmpty,
text: textEmptier,
forceWrite: neverEmpty
};
function neverEmpty(node) {
return [node];
}
function elementEmptier(element) {
var children = removeEmpty(element.children);
if (children.length === 0) {
return [];
} else {
return ast.elementWithTag(element.tag, children);
}
}
function textEmptier(node) {
if (node.value.length === 0) {
return [];
} else {
return [node];
}
}
module.exports = simplify;
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