tiny.smg.tree.runtime.selection

1pub const selection = @import("selection.zig");

1const std = @import("std");2const runtime = @import("root.zig");34const subtree = runtime.subtree;56pub const Accepted = struct {7    root: *const subtree.Subtree,8    branch_precedence: i64,9};1011pub const Decision = struct {12    existing_branch_precedence: ?i64,13    candidate_branch_precedence: i64,14    existing_root_precedence: ?i32,15    candidate_root_precedence: i32,16    order: ?std.math.Order,17    replace: bool,18};1920pub const Trace = struct {21    decisions: std.ArrayList(Decision) = .empty,2223    pub fn deinit(self: *Trace, allocator: std.mem.Allocator) void {24        self.decisions.deinit(allocator);25        self.* = .{};26    }27};2829pub fn consider(30    allocator: std.mem.Allocator,31    accepted: *?Accepted,32    candidate_root: *const subtree.Subtree,33    candidate_branch_precedence: i64,34    trace: ?*Trace,35) !void {36    var tree_order: ?std.math.Order = null;37    const replace = if (accepted.*) |existing| replace: {38        if (candidate_root.dynamic_precedence > existing.root.dynamic_precedence) break :replace true;39        if (candidate_root.dynamic_precedence < existing.root.dynamic_precedence) break :replace false;40        tree_order = try subtree.order(allocator, existing.root, candidate_root);41        break :replace tree_order.? == .gt;42    } else true;43    if (trace) |value| {44        try value.decisions.append(allocator, .{45            .existing_branch_precedence = if (accepted.*) |existing| existing.branch_precedence else null,46            .candidate_branch_precedence = candidate_branch_precedence,47            .existing_root_precedence = if (accepted.*) |existing| existing.root.dynamic_precedence else null,48            .candidate_root_precedence = candidate_root.dynamic_precedence,49            .order = tree_order,50            .replace = replace,51        });52    }53    if (replace) accepted.* = .{ .root = candidate_root, .branch_precedence = candidate_branch_precedence };54}5556test "focused accepted selection uses root dynamic precedence" {57    var retained = testSubtree(2);58    var lower = testSubtree(1);59    var higher = testSubtree(3);60    var accepted: ?Accepted = .{ .root = &retained, .branch_precedence = -10 };61    try consider(std.testing.allocator, &accepted, &lower, 100, null);62    try std.testing.expectEqual(&retained, accepted.?.root);63    try consider(std.testing.allocator, &accepted, &higher, -100, null);64    try std.testing.expectEqual(&higher, accepted.?.root);65}6667fn testSubtree(dynamic_precedence: i32) subtree.Subtree {68    return .{69        .symbol = 1,70        .children = &.{},71        .start = .{ .byte = 0, .point = .{ .row = 0, .column = 0 } },72        .end = .{ .byte = 1, .point = .{ .row = 0, .column = 1 } },73        .production_id = 0,74        .dynamic_precedence = dynamic_precedence,75        .parse_state = 1,76        .visible_descendant_count = 0,77        .named_descendant_count = 0,78        .visible = true,79        .named = true,80        .extra = false,81        .scanner_state = null,82    };83}