tiny.termtex.operator

1const std = @import("std");2const ast = @import("ast.zig");34pub const StretchArrowShaft = enum {5    single,6    double,7    squiggle,8};910pub const StretchArrow = struct {11    left_head: ?[]const u8 = null,12    right_head: ?[]const u8 = null,13    shaft: StretchArrowShaft = .single,14    left_bar: bool = false,15};1617const StretchArrowEntry = struct {18    value: []const u8,19    arrow: StretchArrow,20};2122pub fn limitsBase(expr: *const ast.Expr) bool {23    switch (expr.*) {24        .operator => |value| return switch (value.limit_policy) {25            .auto => limitsBase(value.body),26            .limits => true,27            .nolimits => false,28        },29        .annotation => |value| return value.kind == .overbrace or value.kind == .underbrace,30        else => {},31    }32    const value = ast.textValue(expr) orelse return false;33    return limitsText(value);34}3536pub fn limitsText(value: []const u8) bool {37    inline for (.{38        "∑",39        "∏",40        "∐",41        "lim",42        "max",43        "min",44        "sup",45        "inf",46    }) |candidate| {47        if (std.mem.eql(u8, value, candidate)) return true;48    }49    return stretchArrowText(value) != null;50}5152pub fn displayOperatorText(value: []const u8) bool {53    inline for (.{54        "∑",55        "⨁",56        "⨂",57        "⨀",58        "∏",59        "∐",60        "∫",61        "∬",62        "∭",63        "∮",64        "⋀",65        "⋁",66        "⋃",67        "⋂",68    }) |candidate| {69        if (std.mem.eql(u8, value, candidate)) return true;70    }71    return false;72}7374pub fn stretchArrowBase(expr: *const ast.Expr) ?StretchArrow {75    switch (expr.*) {76        .operator => |value| return switch (value.limit_policy) {77            .auto, .limits => stretchArrowBase(value.body),78            .nolimits => null,79        },80        else => {},81    }82    const value = ast.textValue(expr) orelse return null;83    return stretchArrowText(value);84}8586pub fn stretchArrowText(value: []const u8) ?StretchArrow {87    inline for (stretch_arrows) |entry| {88        if (std.mem.eql(u8, value, entry.value)) return entry.arrow;89    }90    return null;91}9293const stretch_arrows = [_]StretchArrowEntry{94    .{ .value = "→", .arrow = .{ .right_head = "→" } },95    .{ .value = "←", .arrow = .{ .left_head = "←" } },96    .{ .value = "↔", .arrow = .{ .left_head = "←", .right_head = "→" } },97    .{ .value = "⇒", .arrow = .{ .right_head = "⇒", .shaft = .double } },98    .{ .value = "⇐", .arrow = .{ .left_head = "⇐", .shaft = .double } },99    .{ .value = "⇔", .arrow = .{ .left_head = "⇐", .right_head = "⇒", .shaft = .double } },100    .{ .value = "⟶", .arrow = .{ .right_head = "→" } },101    .{ .value = "⟵", .arrow = .{ .left_head = "←" } },102    .{ .value = "⟷", .arrow = .{ .left_head = "←", .right_head = "→" } },103    .{ .value = "⟹", .arrow = .{ .right_head = "⇒", .shaft = .double } },104    .{ .value = "⟸", .arrow = .{ .left_head = "⇐", .shaft = .double } },105    .{ .value = "⟺", .arrow = .{ .left_head = "⇐", .right_head = "⇒", .shaft = .double } },106    .{ .value = "↦", .arrow = .{ .right_head = "→", .left_bar = true } },107    .{ .value = "⟼", .arrow = .{ .right_head = "→", .left_bar = true } },108    .{ .value = "↪", .arrow = .{ .right_head = "↪" } },109    .{ .value = "↩", .arrow = .{ .left_head = "↩" } },110    .{ .value = "↠", .arrow = .{ .right_head = "↠" } },111    .{ .value = "↞", .arrow = .{ .left_head = "↞" } },112    .{ .value = "⇀", .arrow = .{ .right_head = "⇀" } },113    .{ .value = "⇁", .arrow = .{ .right_head = "⇁" } },114    .{ .value = "↼", .arrow = .{ .left_head = "↼" } },115    .{ .value = "↽", .arrow = .{ .left_head = "↽" } },116    .{ .value = "⇌", .arrow = .{ .left_head = "↼", .right_head = "⇁", .shaft = .double } },117    .{ .value = "↝", .arrow = .{ .right_head = "↝", .shaft = .squiggle } },118    .{ .value = "⇝", .arrow = .{ .right_head = "⇝", .shaft = .squiggle } },119    .{ .value = "⊸", .arrow = .{ .right_head = "⊸" } },120};121122test "detect limit-bearing operator bases" {123    var sum = ast.Expr{ .text = "∑" };124    var lim = ast.Expr{ .text = "lim" };125    var x = ast.Expr{ .text = "x" };126    const limited = ast.Expr{ .operator = .{ .body = &x, .limit_policy = .limits } };127    const nolimits = ast.Expr{ .operator = .{ .body = &sum, .limit_policy = .nolimits } };128129    try std.testing.expect(limitsBase(&sum));130    try std.testing.expect(limitsBase(&lim));131    try std.testing.expect(!limitsBase(&x));132    try std.testing.expect(limitsBase(&limited));133    try std.testing.expect(!limitsBase(&nolimits));134    try std.testing.expect(limitsText("max"));135    try std.testing.expect(displayOperatorText("∑"));136    try std.testing.expect(displayOperatorText("∫"));137    try std.testing.expect(!displayOperatorText("lim"));138}139140test "detect stretchable arrow bases" {141    var right = ast.Expr{ .text = "→" };142    var mapsto = ast.Expr{ .text = "↦" };143    var sum = ast.Expr{ .text = "∑" };144    const nolimits = ast.Expr{ .operator = .{ .body = &right, .limit_policy = .nolimits } };145146    try std.testing.expect(stretchArrowBase(&right) != null);147    try std.testing.expect(stretchArrowBase(&mapsto).?.left_bar);148    try std.testing.expect(stretchArrowBase(&sum) == null);149    try std.testing.expect(stretchArrowBase(&nolimits) == null);150}

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