@jinntec/fore
Version:
Fore - declarative user interfaces in plain HTML
380 lines (361 loc) • 11.7 kB
JavaScript
/**
* A simple dependency graph
*
* based on the work of https://github.com/jriecken/dependency-graph but working on ES6.
*
* Furthermore instead of the DepGraphCycleError a compute-exception event is dispatched.
*
*
*/
/**
* Cycle error, including the path of the cycle.
*/
// const DepGraphCycleError = (exports.DepGraphCycleError = function (cyclePath) {
/*
export function DepGraphCycleError(cyclePath) {
const message = "Dependency Cycle Found: " + cyclePath.join(" -> ");
const instance = new Error(message);
instance.cyclePath = cyclePath;
Object.setPrototypeOf(instance, Object.getPrototypeOf(this));
if (Error.captureStackTrace) {
Error.captureStackTrace(instance, DepGraphCycleError);
}
return instance;
};
DepGraphCycleError.prototype = Object.create(Error.prototype, {
constructor: {
value: Error,
enumerable: false,
writable: true,
configurable: true
}
});
Object.setPrototypeOf(DepGraphCycleError, Error);
*/
/**
* Helper for creating a Topological Sort using Depth-First-Search on a set of edges.
*
* Detects cycles and throws an Error if one is detected (unless the "circular"
* parameter is "true" in which case it ignores them).
*
* @param edges The set of edges to DFS through
* @param leavesOnly Whether to only return "leaf" nodes (ones who have no edges)
* @param result An array in which the results will be populated
* @param circular A boolean to allow circular dependencies
*/
function createDFS(edges, leavesOnly, result, circular) {
const visited = {};
// eslint-disable-next-line func-names
return function (start) {
// console.log('start ', start);
if (visited[start]) {
return;
}
const inCurrentPath = {};
const currentPath = [];
const todo = []; // used as a stack
todo.push({ node: start, processed: false });
while (todo.length > 0) {
const current = todo[todo.length - 1]; // peek at the todo stack
const { processed } = current;
const { node } = current;
if (!processed) {
// Haven't visited edges yet (visiting phase)
if (visited[node]) {
todo.pop();
// eslint-disable-next-line no-continue
continue;
} else if (inCurrentPath[node]) {
// It's not a DAG
if (circular) {
todo.pop();
// If we're tolerating cycles, don't revisit the node
// eslint-disable-next-line no-continue
continue;
}
currentPath.push(node);
window.dispatchEvent(
new CustomEvent('compute-exception', {
composed: false,
bubbles: true,
detail: {
path: currentPath,
message: 'cyclic graph',
},
}),
);
// return;
// console.log('‘circular path: ' + currentPath);
// throw new DepGraphCycleError(currentPath);
// Stop all processing. This form is broken and we should not break the browser
throw new Error(`Cyclic at ${currentPath}`);
}
inCurrentPath[node] = true;
currentPath.push(node);
const nodeEdges = edges[node];
// (push edges onto the todo stack in reverse order to be order-compatible with the old DFS implementation)
for (let i = nodeEdges.length - 1; i >= 0; i -= 1) {
todo.push({ node: nodeEdges[i], processed: false });
}
current.processed = true;
} else {
// Have visited edges (stack unrolling phase)
todo.pop();
currentPath.pop();
inCurrentPath[node] = false;
visited[node] = true;
if (!leavesOnly || edges[node].length === 0) {
result.push(node);
}
}
}
};
}
/**
* Simple Dependency Graph
*/
/*
var DepGraph = (exports.DepGraph = function DepGraph(opts) {
this.nodes = {}; // Node -> Node/Data (treated like a Set)
this.outgoingEdges = {}; // Node -> [Dependency Node]
this.incomingEdges = {}; // Node -> [Dependant Node]
this.circular = opts && !!opts.circular; // Allows circular deps
});
*/
export function DepGraph(opts) {
this.nodes = {}; // Node -> Node/Data (treated like a Set)
this.outgoingEdges = {}; // Node -> [Dependency Node]
this.incomingEdges = {}; // Node -> [Dependant Node]
this.circular = opts && !!opts.circular; // Allows circular deps
}
DepGraph.prototype = {
/**
* The number of nodes in the graph.
*/
size() {
return Object.keys(this.nodes).length;
},
/**
* Add a node to the dependency graph. If a node already exists, this method will do nothing.
*/
addNode(node, data) {
if (!this.hasNode(node)) {
// Checking the arguments length allows the user to add a node with undefined data
if (arguments.length === 2) {
this.nodes[node] = data;
} else {
this.nodes[node] = node;
}
this.outgoingEdges[node] = [];
this.incomingEdges[node] = [];
}
},
/**
* Remove a node from the dependency graph. If a node does not exist, this method will do nothing.
*/
removeNode(node) {
if (this.hasNode(node)) {
delete this.nodes[node];
delete this.outgoingEdges[node];
delete this.incomingEdges[node];
// [this.incomingEdges, this.outgoingEdges].forEach(function (edgeList) {
[this.incomingEdges, this.outgoingEdges].forEach(edgeList => {
Object.keys(edgeList).forEach(key => {
const idx = edgeList[key].indexOf(node);
if (idx >= 0) {
edgeList[key].splice(idx, 1);
}
}, this);
});
}
},
/**
* Check if a node exists in the graph
*/
hasNode(node) {
// return this.nodes.hasOwnProperty(node);
return Object.prototype.hasOwnProperty.call(this.nodes, node);
},
/**
* Get the data associated with a node name
*/
getNodeData(node) {
if (this.hasNode(node)) {
return this.nodes[node];
}
throw new Error(`Node does not exist: ${node}`);
},
/**
* Set the associated data for a given node name. If the node does not exist, this method will throw an error
*/
setNodeData(node, data) {
if (this.hasNode(node)) {
this.nodes[node] = data;
} else {
throw new Error(`Node does not exist: ${node}`);
}
},
/**
* Add a dependency between two nodes. If either of the nodes does not exist,
* an Error will be thrown.
*/
addDependency(from, to) {
if (!this.hasNode(from)) {
throw new Error(`Node does not exist: ${from}`);
}
if (!this.hasNode(to)) {
throw new Error(`Node does not exist: ${to}`);
}
if (this.outgoingEdges[from].indexOf(to) === -1) {
this.outgoingEdges[from].push(to);
}
if (this.incomingEdges[to].indexOf(from) === -1) {
this.incomingEdges[to].push(from);
}
return true;
},
/**
* Remove a dependency between two nodes.
*/
removeDependency(from, to) {
let idx;
if (this.hasNode(from)) {
idx = this.outgoingEdges[from].indexOf(to);
if (idx >= 0) {
this.outgoingEdges[from].splice(idx, 1);
}
}
if (this.hasNode(to)) {
idx = this.incomingEdges[to].indexOf(from);
if (idx >= 0) {
this.incomingEdges[to].splice(idx, 1);
}
}
},
/**
* Return a clone of the dependency graph. If any custom data is attached
* to the nodes, it will only be shallow copied.
*/
clone() {
const source = this;
const result = new DepGraph();
const keys = Object.keys(source.nodes);
keys.forEach(n => {
result.nodes[n] = source.nodes[n];
result.outgoingEdges[n] = source.outgoingEdges[n].slice(0);
result.incomingEdges[n] = source.incomingEdges[n].slice(0);
});
return result;
},
/**
* Get an array containing the direct dependencies of the specified node.
*
* Throws an Error if the specified node does not exist.
*/
directDependenciesOf(node) {
if (this.hasNode(node)) {
return this.outgoingEdges[node].slice(0);
}
throw new Error(`Node does not exist: ${node}`);
},
/**
* Get an array containing the nodes that directly depend on the specified node.
*
* Throws an Error if the specified node does not exist.
*/
directDependantsOf(node) {
if (this.hasNode(node)) {
return this.incomingEdges[node].slice(0);
}
throw new Error(`Node does not exist: ${node}`);
},
/**
* Get an array containing the nodes that the specified node depends on (transitively).
*
* Throws an Error if the graph has a cycle, or the specified node does not exist.
*
* If `leavesOnly` is true, only nodes that do not depend on any other nodes will be returned
* in the array.
*/
dependenciesOf(node, leavesOnly) {
if (this.hasNode(node)) {
const result = [];
const DFS = createDFS(this.outgoingEdges, leavesOnly, result, this.circular);
DFS(node);
const idx = result.indexOf(node);
if (idx >= 0) {
result.splice(idx, 1);
}
return result;
}
throw new Error(`Node does not exist: ${node}`);
},
/**
* get an array containing the nodes that depend on the specified node (transitively).
*
* Throws an Error if the graph has a cycle, or the specified node does not exist.
*
* If `leavesOnly` is true, only nodes that do not have any dependants will be returned in the array.
*/
dependantsOf(node, leavesOnly) {
if (this.hasNode(node)) {
const result = [];
const DFS = createDFS(this.incomingEdges, leavesOnly, result, this.circular);
DFS(node);
const idx = result.indexOf(node);
if (idx >= 0) {
result.splice(idx, 1);
}
return result;
}
throw new Error(`Node does not exist: ${node}`);
},
/**
* Get an array of nodes that have no dependants (i.e. nothing depends on them).
*/
entryNodes() {
const self = this;
return Object.keys(this.nodes).filter(node => self.incomingEdges[node].length === 0);
},
/**
* Construct the overall processing order for the dependency graph.
*
* Throws an Error if the graph has a cycle.
*
* If `leavesOnly` is true, only nodes that do not depend on any other nodes will be returned.
*/
overallOrder(leavesOnly) {
const self = this;
const result = [];
const keys = Object.keys(this.nodes);
if (keys.length === 0) {
return result; // Empty graph
}
if (!this.circular) {
// Look for cycles - we run the DFS starting at all the nodes in case there
// are several disconnected subgraphs inside this dependency graph.
const CycleDFS = createDFS(this.outgoingEdges, false, [], this.circular);
keys.forEach(n => {
CycleDFS(n);
});
}
const DFS = createDFS(this.outgoingEdges, leavesOnly, result, this.circular);
// Find all potential starting points (nodes with nothing depending on them) an
// run a DFS starting at these points to get the order
keys
.filter(node => self.incomingEdges[node].length === 0)
.forEach(n => {
DFS(n);
});
// If we're allowing cycles - we need to run the DFS against any remaining
// nodes that did not end up in the initial result (as they are part of a
// subgraph that does not have a clear starting point)
if (this.circular) {
keys.filter(node => result.indexOf(node) === -1).forEach(n => DFS(n));
}
return result;
},
};
// Create some aliases
DepGraph.prototype.directDependentsOf = DepGraph.prototype.directDependantsOf;
DepGraph.prototype.dependentsOf = DepGraph.prototype.dependantsOf;