feat: Added Go style date format configuration.

mustache/pipes.odin

@@ -1,6 +1,7 @@
 package mustache
 
 import "core:fmt"
+import "core:log"
 import "core:reflect"
 import "core:strings"
 import "core:time"
@@ -12,6 +13,8 @@ MAX_PIPES :: 8
 // No filter accepts more than 2 args.
 MAX_PIPE_ARGS :: 2
 
+DEFAULT_DATE_FORMAT :: "2 Jan 2006"
+
 Pipe_Filter :: struct {
 	op:   string,
 	args: [dynamic; MAX_PIPE_ARGS]string,
@@ -111,6 +114,7 @@ apply_pipeline :: proc(
 	current = value
 	for &filter in filters {
 		current = apply_filter(current, &filter, pos, ctx) or_return
+		log.debugf("applied: filter=%v before=%s after=%s pos=%d", filter, value, current, pos)
 	}
 	return
 }
@@ -128,11 +132,42 @@ apply_filter :: proc(value: any, filter: ^Pipe_Filter, pos: int, ctx: []any) ->
 				pos = pos,
 				kind = .Data,
 			}
-		} else {
-			return apply_format(str, filter.args[:], pos)
 		}
+
+		date_format: string
+
+		if len(filter.args) > 0 {
+			date_format = filter.args[0]
+		} else {
+			date_format_raw := resolve_name("date_format", ctx)
+			if date_format_raw == nil {
+				return value, Error_Body {
+					msg = "Unable to determine date format",
+					pos = pos,
+					kind = .Data,
+				}
+			} else {
+				valid: bool
+				date_format, valid = reflect.as_string(date_format_raw)
+				if !valid {
+					return value, Error_Body {
+						msg = "date format is not a string",
+						pos = pos,
+						kind = .Data,
+					}
+				}
+			}
+		}
+
+		str2, err := apply_format(str, filter.args[:], pos, date_format)
+		if err != nil {
+			return value, err
+		} else {
+			return any{new_clone(str2, context.temp_allocator), typeid_of(string)}, nil
+		}
+
 	case:
-		return nil, Error_Body{
+		return nil, Error_Body {
 			msg = fmt.tprintf("unknown pipe op '%s'", filter.op),
 			pos = pos,
 			kind = .Data,
@@ -140,51 +175,40 @@ apply_filter :: proc(value: any, filter: ^Pipe_Filter, pos: int, ctx: []any) ->
 	}
 }
 
-// apply_format formats an ISO 8601 date string as a display string
-// (e.g. "2026-03-15T08:49:54-04:00" → "15 Mar 2026"). Invalid input
-// (empty, too-short, or unparseable) returns a Data-kind `Error`. Templates
-// that need to skip dateless pages should gate with a section:
-//   {{#date}}<time datetime="{{.}}">{{. | format}}</time>{{/date}}
-// The section's truthiness check catches empty before the filter runs.
-//
-// Currently ignores args; planned to accept Go reference-date format
-// strings in the future.
-//
-// Accepts any of these ISO 8601 forms (date prefix is invariant):
-//   2023-10-15T13:18:50-07:00
-//   2023-10-15T13:18:50-0700
-//   2023-10-15T13:18:50Z
-//   2023-10-15T13:18:50
-//   2023-10-15
-apply_format :: proc(iso: string, args: []string, pos: int) -> (result: any, err: Error) {
-	if len(iso) < 10 {
-		return nil, Error_Body{
-			msg = "format may only be used on dates",
-			pos = pos,
-			kind = .Data,
-		}
+apply_format :: proc(
+	iso: string,
+	args: []string,
+	pos: int,
+	date_format: string,
+) -> (
+	result: string,
+	err: Error,
+) {
+	fmt_str := date_format
+	if fmt_str == "" {
+		log.errorf(
+			"format pipe used but no date format configured (set date.format in thor.json) Default will be used",
+		)
+		fmt_str = DEFAULT_DATE_FORMAT
 	}
 
-	year := iso[:4]
-	month_num := (int(iso[5]) - 0x30) * 10 + (int(iso[6]) - 0x30)
-	day_num := (int(iso[8]) - 0x30) * 10 + (int(iso[9]) - 0x30)
-
-	if month_num < 1 || month_num > 12 {
-		return nil, Error_Body{
+	components, ok := parse_iso_date(iso)
+	if !ok {
+		return "", Error_Body {
 			msg = fmt.tprintf("invalid date: \"%s\"", iso),
 			pos = pos,
 			kind = .Data,
 		}
 	}
 
-	month := fmt.tprintf("%s", time.Month(month_num))[:3]
-	return fmt.tprintf("%d %s %s", day_num, month, year), nil
+	log.debugf("date: '%s' format: '%s'", iso, date_format)
+	return format_date(components, fmt_str), nil
 }
 
 // Groups preserve first-appearance order from the input list.
 apply_group_by :: proc(value: any, args: []string, pos: int) -> (result: any, err: Error) {
 	if len(args) != 1 {
-		return nil, Error_Body{
+		return nil, Error_Body {
 			msg = fmt.tprintf("group_by expects 1 argument, got %d", len(args)),
 			pos = pos,
 			kind = .Data,
@@ -194,11 +218,7 @@ apply_group_by :: proc(value: any, args: []string, pos: int) -> (result: any, er
 
 	elem_info, count, data := list_info(value)
 	if elem_info == nil {
-		return nil, Error_Body{
-			msg = "group_by expects a list",
-			pos = pos,
-			kind = .Data,
-		}
+		return nil, Error_Body{msg = "group_by expects a list", pos = pos, kind = .Data}
 	}
 
 	groups := make([dynamic]Group, 0, 8, context.temp_allocator)
@@ -219,7 +239,7 @@ apply_group_by :: proc(value: any, args: []string, pos: int) -> (result: any, er
 		}
 		key_str := any_to_string(key_val)
 		if len(key_str) == 0 {
-			return nil, Error_Body{
+			return nil, Error_Body {
 				msg = fmt.tprintf("group_by: field '%s' is empty", field),
 				pos = pos,
 				kind = .Data,