Placeholder

pub const Placeholder = struct

File

Code

pub const Placeholder = struct {
    specifier_arg: []const u8,
    fill: u8,
    alignment: Alignment,
    arg: Specifier,
    width: Specifier,
    precision: Specifier,

    pub fn parse(comptime bytes: []const u8) Placeholder {
        var parser: Parser = .{ .bytes = bytes, .i = 0 };
        const arg = parser.specifier() catch |err| @compileError(@errorName(err));
        const specifier_arg = parser.until(':');
        if (parser.char()) |b| {
            if (b != ':') @compileError("expected : or }, found '" ++ &[1]u8{b} ++ "'");
        }

        // Parse the fill byte, if present.
        //
        // When the width field is also specified, the fill byte must
        // be followed by an alignment specifier, unless it's '0' (zero)
        // (in which case it's handled as part of the width specifier).
        var fill: ?u8 = if (parser.peek(1)) |b|
            switch (b) {
                '<', '^', '>' => parser.char(),
                else => null,
            }
        else
            null;

        // Parse the alignment parameter
        const alignment: ?Alignment = if (parser.peek(0)) |b| init: {
            switch (b) {
                '<', '^', '>' => {
                    // consume the character
                    break :init switch (parser.char().?) {
                        '<' => .left,
                        '^' => .center,
                        else => .right,
                    };
                },
                else => break :init null,
            }
        } else null;

        // When none of the fill character and the alignment specifier have
        // been provided, check whether the width starts with a zero.
        if (fill == null and alignment == null) {
            fill = if (parser.peek(0) == '0') '0' else null;
        }

        // Parse the width parameter
        const width = parser.specifier() catch |err| @compileError(@errorName(err));

        // Skip the dot, if present
        if (parser.char()) |b| {
            if (b != '.') @compileError("expected . or }, found '" ++ &[1]u8{b} ++ "'");
        }

        // Parse the precision parameter
        const precision = parser.specifier() catch |err| @compileError(@errorName(err));

        if (parser.char()) |b| @compileError("extraneous trailing character '" ++ &[1]u8{b} ++ "'");

        const specifier_array = specifier_arg[0..specifier_arg.len].*;

        return .{
            .specifier_arg = &specifier_array,
            .fill = fill orelse default_fill_char,
            .alignment = alignment orelse default_alignment,
            .arg = arg,
            .width = width,
            .precision = precision,
        };
    }
}