Source
pub fn formatType(
value: anytype,
comptime fmt: []const u8,
options: FormatOptions,
writer: anytype,
max_depth: usize,
) @TypeOf(writer).Error!void {
const T = @TypeOf(value);
const actual_fmt = comptime if (std.mem.eql(u8, fmt, ANY))
defaultSpec(T)
else if (fmt.len != 0 and (fmt[0] == '?' or fmt[0] == '!')) switch (@typeInfo(T)) {
.optional, .error_union => fmt,
else => stripOptionalOrErrorUnionSpec(fmt),
} else fmt;
if (comptime std.mem.eql(u8, actual_fmt, "*")) {
return formatAddress(value, options, writer);
}
if (std.meta.hasMethod(T, "format")) {
return try value.format(actual_fmt, options, writer);
}
switch (@typeInfo(T)) {
.comptime_int, .int, .comptime_float, .float => {
return formatValue(value, actual_fmt, options, writer);
},
.void => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
return formatBuf("void", options, writer);
},
.bool => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
return formatBuf(if (value) "true" else "false", options, writer);
},
.optional => {
if (actual_fmt.len == 0 or actual_fmt[0] != '?')
@compileError("cannot format optional without a specifier (i.e. {?} or {any})");
const remaining_fmt = comptime stripOptionalOrErrorUnionSpec(actual_fmt);
if (value) |payload| {
return formatType(payload, remaining_fmt, options, writer, max_depth);
} else {
return formatBuf("null", options, writer);
}
},
.error_union => {
if (actual_fmt.len == 0 or actual_fmt[0] != '!')
@compileError("cannot format error union without a specifier (i.e. {!} or {any})");
const remaining_fmt = comptime stripOptionalOrErrorUnionSpec(actual_fmt);
if (value) |payload| {
return formatType(payload, remaining_fmt, options, writer, max_depth);
} else |err| {
return formatType(err, "", options, writer, max_depth);
}
},
.error_set => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
try writer.writeAll("error.");
return writer.writeAll(@errorName(value));
},
.@"enum" => |enumInfo| {
try writer.writeAll(@typeName(T));
if (enumInfo.is_exhaustive) {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
try writer.writeAll(".");
try writer.writeAll(@tagName(value));
return;
}
// Use @tagName only if value is one of known fields
@setEvalBranchQuota(3 * enumInfo.fields.len);
inline for (enumInfo.fields) |enumField| {
if (@intFromEnum(value) == enumField.value) {
try writer.writeAll(".");
try writer.writeAll(@tagName(value));
return;
}
}
try writer.writeAll("(");
try formatType(@intFromEnum(value), actual_fmt, options, writer, max_depth);
try writer.writeAll(")");
},
.@"union" => |info| {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
try writer.writeAll(@typeName(T));
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
if (info.tag_type) |UnionTagType| {
try writer.writeAll("{ .");
try writer.writeAll(@tagName(@as(UnionTagType, value)));
try writer.writeAll(" = ");
inline for (info.fields) |u_field| {
if (value == @field(UnionTagType, u_field.name)) {
try formatType(@field(value, u_field.name), ANY, options, writer, max_depth - 1);
}
}
try writer.writeAll(" }");
} else {
try format(writer, "@{x}", .{@intFromPtr(&value)});
}
},
.@"struct" => |info| {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
if (info.is_tuple) {
// Skip the type and field names when formatting tuples.
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
try writer.writeAll("{");
inline for (info.fields, 0..) |f, i| {
if (i == 0) {
try writer.writeAll(" ");
} else {
try writer.writeAll(", ");
}
try formatType(@field(value, f.name), ANY, options, writer, max_depth - 1);
}
return writer.writeAll(" }");
}
try writer.writeAll(@typeName(T));
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
try writer.writeAll("{");
inline for (info.fields, 0..) |f, i| {
if (i == 0) {
try writer.writeAll(" .");
} else {
try writer.writeAll(", .");
}
try writer.writeAll(f.name);
try writer.writeAll(" = ");
try formatType(@field(value, f.name), ANY, options, writer, max_depth - 1);
}
try writer.writeAll(" }");
},
.pointer => |ptr_info| switch (ptr_info.size) {
.one => switch (@typeInfo(ptr_info.child)) {
.array, .@"enum", .@"union", .@"struct" => {
return formatType(value.*, actual_fmt, options, writer, max_depth);
},
else => return format(writer, "{s}@{x}", .{ @typeName(ptr_info.child), @intFromPtr(value) }),
},
.many, .c => {
if (actual_fmt.len == 0)
@compileError("cannot format pointer without a specifier (i.e. {s} or {*})");
if (ptr_info.sentinel() != null) {
return formatType(mem.span(value), actual_fmt, options, writer, max_depth);
}
if (actual_fmt[0] == 's' and ptr_info.child == u8) {
return formatBuf(mem.span(value), options, writer);
}
invalidFmtError(fmt, value);
},
.slice => {
if (actual_fmt.len == 0)
@compileError("cannot format slice without a specifier (i.e. {s} or {any})");
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
if (actual_fmt[0] == 's' and ptr_info.child == u8) {
return formatBuf(value, options, writer);
}
try writer.writeAll("{ ");
for (value, 0..) |elem, i| {
try formatType(elem, actual_fmt, options, writer, max_depth - 1);
if (i != value.len - 1) {
try writer.writeAll(", ");
}
}
try writer.writeAll(" }");
},
},
.array => |info| {
if (actual_fmt.len == 0)
@compileError("cannot format array without a specifier (i.e. {s} or {any})");
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
if (actual_fmt[0] == 's' and info.child == u8) {
return formatBuf(&value, options, writer);
}
try writer.writeAll("{ ");
for (value, 0..) |elem, i| {
try formatType(elem, actual_fmt, options, writer, max_depth - 1);
if (i < value.len - 1) {
try writer.writeAll(", ");
}
}
try writer.writeAll(" }");
},
.vector => |info| {
if (max_depth == 0) {
return writer.writeAll("{ ... }");
}
try writer.writeAll("{ ");
var i: usize = 0;
while (i < info.len) : (i += 1) {
try formatType(value[i], actual_fmt, options, writer, max_depth - 1);
if (i < info.len - 1) {
try writer.writeAll(", ");
}
}
try writer.writeAll(" }");
},
.@"fn" => @compileError("unable to format function body type, use '*const " ++ @typeName(T) ++ "' for a function pointer type"),
.type => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
return formatBuf(@typeName(value), options, writer);
},
.enum_literal => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
const buffer = [_]u8{'.'} ++ @tagName(value);
return formatBuf(buffer, options, writer);
},
.null => {
if (actual_fmt.len != 0) invalidFmtError(fmt, value);
return formatBuf("null", options, writer);
},
else => @compileError("unable to format type '" ++ @typeName(T) ++ "'"),
}
}