feat(2024): add Graph data structure

Author: guidoschmidt

2024/Graph.zig

@@ -0,0 +1,69 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
+allocator: Allocator,
+links: std.StringHashMap(std.BufSet),
+
+const Self = @This();
+
+pub fn init(allocator: Allocator) Self {
+    return Self{
+        .links = std.StringHashMap(std.BufSet).init(allocator),
+        .allocator = allocator,
+    };
+}
+
+pub fn addLink(self: *Self, u: []const u8, v: []const u8) !void {
+    if (self.links.contains(u)) {
+        try self.links.getPtr(u).?.insert(v);
+    } else {
+        var bufset = std.BufSet.init(self.allocator);
+        try bufset.insert(v);
+        try self.links.put(u, bufset);
+    }
+}
+
+pub fn format(self: Self, comptime fmt: []const u8, options: std.fmt.FormatOptions, writer: anytype) !void {
+    _ = fmt;
+    _ = options;
+    var links_it = self.links.iterator();
+    while (links_it.next()) |e| {
+        const u = e.key_ptr.*;
+        try writer.print("\n{s}\n  └[", .{u});
+        var v_it = e.value_ptr.iterator();
+        while (v_it.next()) |v| {
+            try writer.print("{s},", .{v.*});
+        }
+        try writer.print("]", .{});
+    }
+}
+
+pub fn toDotFile(self: *Self, allocator: Allocator) !void {
+    const file_path = "graph.dot";
+    const file = try std.fs.cwd().createFile(file_path, .{});
+    var fw = file.writer();
+
+    try fw.print("strict digraph G {{", .{});
+    var it = self.links.iterator();
+    while (it.next()) |e| {
+        const u = e.key_ptr.*;
+        try fw.print("\n  {s} -> {{", .{u});
+        var v_it = e.value_ptr.iterator();
+        while (v_it.next()) |v| {
+            try fw.print("{s} ", .{v.*});
+        }
+        try fw.print("}}", .{});
+    }
+    try fw.print("\n}}", .{});
+
+    // Try to run 'dot' command to compile .dot file to svg
+    var child_process = std.process.Child.init(&[_][]const u8{ "dot", "-Tsvg", file_path, "-o", "graph.svg" }, allocator);
+    child_process.stdout_behavior = .Pipe;
+    child_process.stderr_behavior = .Pipe;
+    try child_process.spawn();
+    _ = try child_process.wait();
+}
+
+pub fn findCliques(self: *Self) void {
+    _ = self;
+}