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add month day name parsers
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@FObersteiner
FObersteiner committed Oct 9, 2024
1 parent 7df4fbd commit 31f3a81
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5 changes: 5 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,11 @@ Types of changes

## Unreleased

### Added

- parser for locale-sepcific day and month names
- (internal) handle parser flags as an enum

### Changed

- (internal) clean-up of month/day name functions
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108 changes: 87 additions & 21 deletions lib/string.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,18 @@ const TokenizerState = enum(u8) {
const token_start: u8 = '%';
const modifier: u8 = ':';

const ParserFlags = enum(u32) {
OK = 0,
AM = 1,
PM = 2,
clock_12h = 4,
};

/// Tokenize the parsing directives and parse the datetime string accordingly.
pub fn tokenizeAndParse(data: []const u8, directives: []const u8) !Datetime {
var fmt_idx: usize = 0;
var data_idx: usize = 0;
var am_pm_flags: u8 = 0; // bits; 0 - am, 1 - pm, 2 - found %I
var flags: u32 = 0; // see ParserFlags
var fields = Datetime.Fields{};

// Zig 0.13 :
Expand Down Expand Up @@ -62,15 +69,15 @@ pub fn tokenizeAndParse(data: []const u8, directives: []const u8) !Datetime {
continue :tokenize;
},
.ProcessDirective => {
try parseIntoFields(&fields, data, directives[fmt_idx], &data_idx, &am_pm_flags);
try parseIntoFields(&fields, data, directives[fmt_idx], &data_idx, &flags);
fmt_idx += 1;
state = .ExpectChar;
continue :tokenize;
},
}
}
if (data_idx != data.len) return error.InvalidFormat;
switch (am_pm_flags) {
switch (flags) {
0b000 => {}, // neither %I nor am/pm in input string
0b101 => fields.hour = fields.hour % 12, // %I and 'am'
0b110 => fields.hour = fields.hour % 12 + 12, // %I and 'pm'
Expand Down Expand Up @@ -211,16 +218,19 @@ fn parseIntoFields(
string: []const u8,
directive: u8,
idx_ptr: *usize,
am_pm_flags: *u8,
flags: *u32,
) !void {
switch (directive) {
'd' => fields.day = try parseDigits(u8, string, idx_ptr, 2),
// 'e' - use 'd'
// 'a', // locale-specific, day name short
// 'A', // locale-specific, day name

// TODO : result should not be ignored...
'a' => _ = try parseDayNameAbbr(string, idx_ptr),
'A' => _ = try parseDayName(string, idx_ptr),

'm' => fields.month = try parseDigits(u8, string, idx_ptr, 2),
// 'b', // locale-specific, month name short
// 'B', // locale-specific, month name
'b' => fields.month = try parseMonthNameAbbr(string, idx_ptr),
'B' => fields.month = try parseMonthName(string, idx_ptr),
'Y' => fields.year = try parseDigits(u16, string, idx_ptr, 4),
'y' => fields.year = try parseDigits(u16, string, idx_ptr, 2) + Datetime.century,
// 'C', - formatting-only
Expand All @@ -229,11 +239,11 @@ fn parseIntoFields(
// 'k' - use 'H'
'I' => fields.hour = blk: { // must be in [1..12]
const h = try parseDigits(u8, string, idx_ptr, 2);
am_pm_flags.* |= 4;
flags.* |= @intFromEnum(ParserFlags.clock_12h);
if (h >= 1 and h <= 12) break :blk h else return error.InvalidFormat;
},
'P' => am_pm_flags.* |= try parseAmPm(string, idx_ptr),
'p' => am_pm_flags.* |= try parseAmPm(string, idx_ptr),
'P' => flags.* |= @intFromEnum(try parseAmPm(string, idx_ptr)),
'p' => flags.* |= @intFromEnum(try parseAmPm(string, idx_ptr)),
'M' => fields.minute = try parseDigits(u8, string, idx_ptr, 2),
'S' => fields.second = try parseDigits(u8, string, idx_ptr, 2),
'f' => {
Expand Down Expand Up @@ -414,13 +424,13 @@ fn parseDigits(comptime T: type, string: []const u8, idx_ptr: *usize, maxDigits:
}

// AM or PM string, no matter if upper or lower case.
fn parseAmPm(string: []const u8, idx_ptr: *usize) !u8 {
fn parseAmPm(string: []const u8, idx_ptr: *usize) !ParserFlags {
if (idx_ptr.* + 2 > string.len) return error.InvalidFormat;

var flag: u8 = 0;
var flag = ParserFlags.OK;
flag = switch (std.ascii.toLower(string[idx_ptr.*])) {
'a' => 1,
'p' => 2,
'a' => ParserFlags.AM,
'p' => ParserFlags.PM,
else => return error.InvalidFormat,
};

Expand Down Expand Up @@ -688,25 +698,25 @@ fn getMonthName(n: u8) ![sz_normal]u8 {
// since locale-specific names might change at runtime,
// we need to obtain them at runtime.

pub fn allDayNames() ![7][sz_normal]u8 {
fn allDayNames() ![7][sz_normal]u8 {
var result: [7][sz_normal]u8 = undefined;
for (result, 0..) |_, i| result[i] = try getDayName(@truncate(i));
return result;
}

pub fn allDayNamesShort() ![7][sz_abbr]u8 {
fn allDayNamesShort() ![7][sz_abbr]u8 {
var result: [7][sz_abbr]u8 = undefined;
for (result, 0..) |_, i| result[i] = try getDayNameAbbr(@truncate(i));
return result;
}

pub fn allMonthNames() ![12][sz_normal]u8 {
fn allMonthNames() ![12][sz_normal]u8 {
var result: [12][sz_normal]u8 = undefined;
for (result, 0..) |_, i| result[i] = try getMonthName(@truncate(i));
return result;
}

pub fn allMonthNamesShort() ![12][sz_abbr]u8 {
fn allMonthNamesShort() ![12][sz_abbr]u8 {
var result: [12][sz_abbr]u8 = undefined;
for (result, 0..) |_, i| result[i] = try getMonthNameAbbr(@truncate(i));
return result;
Expand All @@ -715,7 +725,7 @@ pub fn allMonthNamesShort() ![12][sz_abbr]u8 {
test "all names" {
const dnames = try allDayNames();
for (dnames) |n| {
try testing.expect(n[0] != '?'); // default if error
try testing.expect(n[0] != '?'); // '?' is default if error
try testing.expect(n[1] != 0); // assume at least 2 characters
}
const dnames_short = try allDayNamesShort();
Expand All @@ -735,7 +745,63 @@ test "all names" {
}
}

/// test if 'string' starts with the characters from 'target', beginning at idx.
fn parseDayName(string: []const u8, idx_ptr: *usize) !u8 {
const allnames = try allDayNames();
var daynum: u8 = 0;
while (daynum < 7) : (daynum += 1) {
if (strStartswith(string, idx_ptr, std.mem.sliceTo(&allnames[daynum], 0)))
return daynum;
}
return error.InvalidFormat;
}

fn parseDayNameAbbr(string: []const u8, idx_ptr: *usize) !u8 {
const allnames = try allDayNamesShort();
var daynum: u8 = 0;
while (daynum < 7) : (daynum += 1) {
if (strStartswith(string, idx_ptr, std.mem.sliceTo(&allnames[daynum], 0)))
return daynum;
}
return error.InvalidFormat;
}

fn parseMonthName(string: []const u8, idx_ptr: *usize) !u8 {
const allnames = try allMonthNames();
var monthnum: u8 = 0;
while (monthnum < 12) : (monthnum += 1) {
if (strStartswith(string, idx_ptr, std.mem.sliceTo(&allnames[monthnum], 0)))
return monthnum + 1;
}
return error.InvalidFormat;
}

fn parseMonthNameAbbr(string: []const u8, idx_ptr: *usize) !u8 {
const allnames = try allMonthNamesShort();
var monthnum: u8 = 0;
while (monthnum < 12) : (monthnum += 1) {
if (strStartswith(string, idx_ptr, std.mem.sliceTo(&allnames[monthnum], 0)))
return monthnum + 1;
}
return error.InvalidFormat;
}

test "day / month name in string to day / month number" {
var idx: usize = 8;
const string = "...text Monday Tue December Mar text...";
var n = try parseDayName(string, &idx);
try testing.expectEqual(1, n);
idx += 1;
n = try parseDayNameAbbr(string, &idx);
try testing.expectEqual(2, n);
idx += 1;
n = try parseMonthName(string, &idx);
try testing.expectEqual(12, n);
idx += 1;
n = try parseMonthNameAbbr(string, &idx);
try testing.expectEqual(3, n);
}

/// Look if 'string' starts with the characters from 'target', beginning at idx.
/// Advance idx by target.len characters if true.
///
/// An empty input to 'string' or 'target' is considered false.
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48 changes: 48 additions & 0 deletions tests/test_string.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -596,6 +596,54 @@ test "comptime parse with comptime format string, am/pm and 12-hour input" {
}
}

test "parse with abbreviated month and day name, locale-specific" {
if (!locale_ok()) return error.SkipZigTest;

const cases = [_]TestCase{
.{
.string = "Thu 01 Jan 1970, 12 am",
.dt = try Datetime.fromFields(.{ .year = 1970 }),
},
.{
.string = "Thu 18 Feb 2021, 11 AM",
.dt = try Datetime.fromFields(.{ .year = 2021, .month = 2, .day = 18, .hour = 11 }),
},
.{
.string = "Fri 31 Dec 2021, 5 pm",
.dt = try Datetime.fromFields(.{ .year = 2021, .month = 12, .day = 31, .hour = 17 }),
},
};

inline for (cases) |case| {
const dt = try Datetime.fromString(case.string, "%a %d %b %Y, %I %p");
try testing.expectEqual(case.dt, dt);
}
}

test "parse with month name and day, locale-specific" {
if (!locale_ok()) return error.SkipZigTest;

const cases = [_]TestCase{
.{
.string = "Thursday 01 January 1970, 12 am",
.dt = try Datetime.fromFields(.{ .year = 1970 }),
},
.{
.string = "Thursday 18 February 2021, 11 AM",
.dt = try Datetime.fromFields(.{ .year = 2021, .month = 2, .day = 18, .hour = 11 }),
},
.{
.string = "Friday 31 December 2021, 5 pm",
.dt = try Datetime.fromFields(.{ .year = 2021, .month = 12, .day = 31, .hour = 17 }),
},
};

inline for (cases) |case| {
const dt = try Datetime.fromString(case.string, "%A %d %B %Y, %I %p");
try testing.expectEqual(case.dt, dt);
}
}

test "parse %I and am/pm errors" {
var err = Datetime.fromString("19 am", "%I %p"); // invalid hour
try testing.expectError(error.InvalidFormat, err);
Expand Down

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