morca

morca · API

orca.graph

A directed graph drawn as SVG, on the server: the pipelines and datasets that feed each other, and a snapshot's lineage.

Nodes are laid out top to bottom, a row of boxes per level: a node's level is its longest path from a node with no edge in (such a node itself just above the first node it points to), and arrows point down. A level holds at most PER_ROW boxes side by side and wraps onto more rows, so the drawing is about as wide as a phone and grows downward with the graph's depth. In a level, nodes are ordered by where the nodes pointing to them are, then as given, which keeps most arrows short and uncrossed. Each node is a box with a label, a second line, a kind (dataset, pipeline or snapshot, which the stylesheet shapes) and optionally a link and a class, such as start for the snapshot a lineage page is about. Edges that close a cycle (a pipeline that reads the dataset it writes, back_edges) are drawn round the right-hand side, back up, and don't move a node down.

Structs

Node

struct Node

Implements Copyable, Movable

Fields
label: String
sub: String
kind: String
href: String: Empty for no link.
cls: String: An extra class, or empty.
title: String: Its tooltip; empty for the label and the second line.

__init__

def __init__(out self, label: String, sub: String, kind: String, href: String, cls: String, title: String = "")

Edge

struct Edge

Implements Copyable, Movable

Fields
src: Int
dst: Int

Functions

back_edges

def back_edges(n: Int, edges: List[Edge]) -> List[Bool]

Which edges close a cycle: those a depth-first walk, from each node in the order given, finds pointing back to a node it is still inside. Without them the graph has no cycle.

graph_svg

def graph_svg(nodes: List[Node], edges: List[Edge], label: String) -> String

The graph as an <svg> element, sized to fit; label names it for screen readers.

Aliases

comptime PER_ROW = 2

Boxes side by side at most: two fit a phone's width.