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fmt: Refactor the arg fetching code

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* Error out if the requested index is out-of-bound
* Tidy-up all the arg-related variables in a struct
This commit is contained in:
LemonBoy 2020-01-30 22:25:33 +01:00 committed by Andrew Kelley
parent 13f7824266
commit d27678fe83
1 changed files with 31 additions and 28 deletions
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59
lib/std/fmt.zig
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@ -21,17 +21,6 @@ pub const FormatOptions = struct {
fill: u8 = ' ',
};
fn nextArg(comptime used_pos_args: *u32, comptime maybe_pos_arg: ?comptime_int, comptime next_arg: *comptime_int) comptime_int {
if (maybe_pos_arg) |pos_arg| {
used_pos_args.* |= 1 << pos_arg;
return pos_arg;
} else {
const arg = next_arg.*;
next_arg.* += 1;
return arg;
}
}
fn peekIsAlign(comptime fmt: []const u8) bool {
// Should only be called during a state transition to the format segment.
comptime assert(fmt[0] == ':');
@ -113,12 +102,36 @@ pub fn format(
comptime var start_index = 0;
comptime var state = State.Start;
comptime var next_arg = 0;
comptime var maybe_pos_arg: ?comptime_int = null;
comptime var used_pos_args: ArgSetType = 0;
comptime var specifier_start = 0;
comptime var specifier_end = 0;
comptime var options = FormatOptions{};
comptime var arg_state: struct {
next_arg: usize = 0,
used_args: ArgSetType = 0,
args_len: usize = args.len,
fn hasUnusedArgs(comptime self: *@This()) bool {
return (@popCount(ArgSetType, self.used_args) != self.args_len);
}
fn nextArg(comptime self: *@This(), comptime pos_arg: ?comptime_int) comptime_int {
const next_idx = pos_arg orelse blk: {
const arg = self.next_arg;
self.next_arg += 1;
break :blk arg;
};
if (next_idx >= self.args_len) {
@compileError("Too few arguments");
}
// Mark this argument as used
self.used_args |= 1 << next_idx;
return next_idx;
}
} = .{};
inline for (fmt) |c, i| {
switch (state) {
@ -166,11 +179,7 @@ pub fn format(
}
},
'}' => {
const arg_to_print = comptime nextArg(&used_pos_args, maybe_pos_arg, &next_arg);
if (arg_to_print >= args.len) {
@compileError("Too few arguments");
}
const arg_to_print = comptime arg_state.nextArg(maybe_pos_arg);
try formatType(
args[arg_to_print],
@ -203,7 +212,7 @@ pub fn format(
state = if (comptime peekIsAlign(fmt[i..])) State.FormatFillAndAlign else State.FormatWidth;
},
'}' => {
const arg_to_print = comptime nextArg(&used_pos_args, maybe_pos_arg, &next_arg);
const arg_to_print = comptime arg_state.nextArg(maybe_pos_arg);
try formatType(
args[arg_to_print],
@ -250,7 +259,7 @@ pub fn format(
state = .FormatPrecision;
},
'}' => {
const arg_to_print = comptime nextArg(&used_pos_args, maybe_pos_arg, &next_arg);
const arg_to_print = comptime arg_state.nextArg(maybe_pos_arg);
try formatType(
args[arg_to_print],
@ -278,7 +287,7 @@ pub fn format(
options.precision.? += c - '0';
},
'}' => {
const arg_to_print = comptime nextArg(&used_pos_args, maybe_pos_arg, &next_arg);
const arg_to_print = comptime arg_state.nextArg(maybe_pos_arg);
try formatType(
args[arg_to_print],
@ -299,13 +308,7 @@ pub fn format(
}
}
comptime {
// All arguments must have been printed but we allow mixing positional and fixed to achieve this.
var i: usize = 0;
inline while (i < next_arg) : (i += 1) {
used_pos_args |= 1 << i;
}
if (@popCount(ArgSetType, used_pos_args) != args.len) {
if (comptime arg_state.hasUnusedArgs()) {
@compileError("Unused arguments");
}
if (state != State.Start) {