terminal/tmux: add output format parsing (minimal)

src/terminal/tmux.zig

@@ -2,6 +2,7 @@
 
 const control = @import("tmux/control.zig");
 const layout = @import("tmux/layout.zig");
+pub const output = @import("tmux/output.zig");
 pub const ControlParser = control.Parser;
 pub const ControlNotification = control.Notification;
 pub const Layout = layout.Layout;

src/terminal/tmux/output.zig

@@ -0,0 +1,205 @@
+const std = @import("std");
+const testing = std.testing;
+
+pub const ParseError = error{
+    MissingEntry,
+    ExtraEntry,
+    FormatError,
+};
+
+/// Parse the output from a command with the given format struct
+/// (returned usually by FormatStruct). The format struct is expected
+/// to be in the order of the variables used in the format string and
+/// the variables are expected to be plain variables (no conditionals,
+/// extra formatting, etc.). Each variable is expected to be separated
+/// by a single `delimiter` character.
+pub fn parseFormatStruct(
+    comptime T: type,
+    str: []const u8,
+    delimiter: u8,
+) ParseError!T {
+    // Parse all our fields
+    const fields = @typeInfo(T).@"struct".fields;
+    var it = std.mem.splitScalar(u8, str, delimiter);
+    var result: T = undefined;
+    inline for (fields) |field| {
+        const part = it.next() orelse return error.MissingEntry;
+        @field(result, field.name) = Variable.parse(
+            @field(Variable, field.name),
+            part,
+        ) catch return error.FormatError;
+    }
+
+    // We should have consumed all parts now.
+    if (it.next() != null) return error.ExtraEntry;
+
+    return result;
+}
+
+/// Returns a struct type that contains fields for each of the given
+/// format variables. This can be used with `parseFormatStruct` to
+/// parse an output string into a format struct.
+pub fn FormatStruct(comptime vars: []const Variable) type {
+    var fields: [vars.len]std.builtin.Type.StructField = undefined;
+    for (vars, &fields) |variable, *field| {
+        field.* = .{
+            .name = @tagName(variable),
+            .type = variable.Type(),
+            .default_value_ptr = null,
+            .is_comptime = false,
+            .alignment = @alignOf(variable.Type()),
+        };
+    }
+
+    return @Type(.{ .@"struct" = .{
+        .layout = .auto,
+        .fields = &fields,
+        .decls = &.{},
+        .is_tuple = false,
+    } });
+}
+
+/// Possible variables in a tmux format string that we support.
+///
+/// Tmux supports a large number of variables, but we only implement
+/// a subset of them here that are relevant to the use case of implementing
+/// control mode for terminal emulators.
+pub const Variable = enum {
+    session_id,
+    window_id,
+    window_width,
+    window_height,
+    window_layout,
+
+    /// Parse the given string value into the appropriate resulting
+    /// type for this variable.
+    pub fn parse(comptime self: Variable, value: []const u8) !Type(self) {
+        return switch (self) {
+            .session_id => if (value.len >= 2 and value[0] == '$')
+                try std.fmt.parseInt(usize, value[1..], 10)
+            else
+                return error.FormatError,
+            .window_id => if (value.len >= 2 and value[0] == '@')
+                try std.fmt.parseInt(usize, value[1..], 10)
+            else
+                return error.FormatError,
+            .window_width => try std.fmt.parseInt(usize, value, 10),
+            .window_height => try std.fmt.parseInt(usize, value, 10),
+            .window_layout => value,
+        };
+    }
+
+    /// The type of the parsed value for this variable type.
+    pub fn Type(comptime self: Variable) type {
+        return switch (self) {
+            .session_id => usize,
+            .window_id => usize,
+            .window_width => usize,
+            .window_height => usize,
+            .window_layout => []const u8,
+        };
+    }
+};
+
+test "parse session id" {
+    try testing.expectEqual(42, try Variable.parse(.session_id, "$42"));
+    try testing.expectEqual(0, try Variable.parse(.session_id, "$0"));
+    try testing.expectError(error.FormatError, Variable.parse(.session_id, "0"));
+    try testing.expectError(error.FormatError, Variable.parse(.session_id, "@0"));
+    try testing.expectError(error.FormatError, Variable.parse(.session_id, "$"));
+    try testing.expectError(error.FormatError, Variable.parse(.session_id, ""));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.session_id, "$abc"));
+}
+
+test "parse window id" {
+    try testing.expectEqual(42, try Variable.parse(.window_id, "@42"));
+    try testing.expectEqual(0, try Variable.parse(.window_id, "@0"));
+    try testing.expectEqual(12345, try Variable.parse(.window_id, "@12345"));
+    try testing.expectError(error.FormatError, Variable.parse(.window_id, "0"));
+    try testing.expectError(error.FormatError, Variable.parse(.window_id, "$0"));
+    try testing.expectError(error.FormatError, Variable.parse(.window_id, "@"));
+    try testing.expectError(error.FormatError, Variable.parse(.window_id, ""));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.window_id, "@abc"));
+}
+
+test "parse window width" {
+    try testing.expectEqual(80, try Variable.parse(.window_width, "80"));
+    try testing.expectEqual(0, try Variable.parse(.window_width, "0"));
+    try testing.expectEqual(12345, try Variable.parse(.window_width, "12345"));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.window_width, "abc"));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.window_width, "80px"));
+    try testing.expectError(error.Overflow, Variable.parse(.window_width, "-1"));
+}
+
+test "parse window height" {
+    try testing.expectEqual(24, try Variable.parse(.window_height, "24"));
+    try testing.expectEqual(0, try Variable.parse(.window_height, "0"));
+    try testing.expectEqual(12345, try Variable.parse(.window_height, "12345"));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.window_height, "abc"));
+    try testing.expectError(error.InvalidCharacter, Variable.parse(.window_height, "24px"));
+    try testing.expectError(error.Overflow, Variable.parse(.window_height, "-1"));
+}
+
+test "parse window layout" {
+    try testing.expectEqualStrings("abc123", try Variable.parse(.window_layout, "abc123"));
+    try testing.expectEqualStrings("", try Variable.parse(.window_layout, ""));
+    try testing.expectEqualStrings("a]b,c{d}e(f)", try Variable.parse(.window_layout, "a]b,c{d}e(f)"));
+}
+
+test "parseFormatStruct single field" {
+    const T = FormatStruct(&.{.session_id});
+    const result = try parseFormatStruct(T, "$42", ' ');
+    try testing.expectEqual(42, result.session_id);
+}
+
+test "parseFormatStruct multiple fields" {
+    const T = FormatStruct(&.{ .session_id, .window_id, .window_width, .window_height });
+    const result = try parseFormatStruct(T, "$1 @2 80 24", ' ');
+    try testing.expectEqual(1, result.session_id);
+    try testing.expectEqual(2, result.window_id);
+    try testing.expectEqual(80, result.window_width);
+    try testing.expectEqual(24, result.window_height);
+}
+
+test "parseFormatStruct with string field" {
+    const T = FormatStruct(&.{ .window_id, .window_layout });
+    const result = try parseFormatStruct(T, "@5,abc123", ',');
+    try testing.expectEqual(5, result.window_id);
+    try testing.expectEqualStrings("abc123", result.window_layout);
+}
+
+test "parseFormatStruct different delimiter" {
+    const T = FormatStruct(&.{ .window_width, .window_height });
+    const result = try parseFormatStruct(T, "120\t40", '\t');
+    try testing.expectEqual(120, result.window_width);
+    try testing.expectEqual(40, result.window_height);
+}
+
+test "parseFormatStruct missing entry" {
+    const T = FormatStruct(&.{ .session_id, .window_id });
+    try testing.expectError(error.MissingEntry, parseFormatStruct(T, "$1", ' '));
+}
+
+test "parseFormatStruct extra entry" {
+    const T = FormatStruct(&.{.session_id});
+    try testing.expectError(error.ExtraEntry, parseFormatStruct(T, "$1 @2", ' '));
+}
+
+test "parseFormatStruct format error" {
+    const T = FormatStruct(&.{.session_id});
+    try testing.expectError(error.FormatError, parseFormatStruct(T, "42", ' '));
+    try testing.expectError(error.FormatError, parseFormatStruct(T, "@42", ' '));
+    try testing.expectError(error.FormatError, parseFormatStruct(T, "$abc", ' '));
+}
+
+test "parseFormatStruct empty string" {
+    const T = FormatStruct(&.{.session_id});
+    try testing.expectError(error.FormatError, parseFormatStruct(T, "", ' '));
+}
+
+test "parseFormatStruct with empty layout field" {
+    const T = FormatStruct(&.{ .session_id, .window_layout });
+    const result = try parseFormatStruct(T, "$1,", ',');
+    try testing.expectEqual(1, result.session_id);
+    try testing.expectEqualStrings("", result.window_layout);
+}