From e2795d1a1b096b4846270941c4a202fb82b325f0 Mon Sep 17 00:00:00 2001
From: Rex Zeng <rex@rexskz.info>
Date: Mon, 3 Mar 2025 22:56:55 +0800
Subject: [PATCH] fix: no empty string matches

Close #47
---
 rules/rules.go               |  2 +-
 rules/zh/exact_month_date.go | 41 +++++++++++++++++++++++++-----------
 rules/zh/weekday_test.go     |  2 +-
 3 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/rules/rules.go b/rules/rules.go
index 2011d3f..e03f035 100644
--- a/rules/rules.go
+++ b/rules/rules.go
@@ -74,7 +74,7 @@ func (f *F) Find(text string) *Match {
 		}
 	}
 
-	if len(m.Captures) == 0 {
+	if len(m.Captures) == 0 || m.Left == -1 {
 		return nil
 	}
 
diff --git a/rules/zh/exact_month_date.go b/rules/zh/exact_month_date.go
index 3bfccb5..79bfe21 100644
--- a/rules/zh/exact_month_date.go
+++ b/rules/zh/exact_month_date.go
@@ -19,13 +19,17 @@ func ExactMonthDate(s rules.Strategy) rules.Rule {
 		RegExp: regexp.MustCompile("" +
 			"(?:\\b|^)" + // can't use \W here due to Chinese characters
 			"(?:" +
-			"(1[0-2]|[1-9]|" + MON_WORDS_PATTERN + ")" + "(?:\\s*)" +
-			"(月|-|/|\\.)" + "(?:\\s*)" +
+			"(1[0-2]|[1-9])" + "\\s*" + "(?:-|/|\\.)" + "\\s*" + "(1[0-9]|2[0-9]|3[0-1]|[1-9])" +
+			"|" +
+			"(?:" +
+			"(1[0-2]|[1-9]|" + MON_WORDS_PATTERN + ")" + "\\s*" +
+			"(月)" + "\\s*" +
 			")?" +
 			"(?:" +
-			"(1[0-9]|2[0-9]|3[0-1]|[1-9]|" + DAY_WORDS_PATTERN + ")" + "(?:\\s*)" +
-			"(日|号)?" +
-			")?",
+			"(1[0-9]|2[0-9]|3[0-1]|[1-9]|" + DAY_WORDS_PATTERN + ")" + "\\s*" +
+			"(日|号)" +
+			")?" +
+			")",
 		),
 
 		Applier: func(m *rules.Match, c *rules.Context, o *rules.Options, ref time.Time) (bool, error) {
@@ -38,14 +42,14 @@ func ExactMonthDate(s rules.Strategy) rules.Rule {
 			var dayInt = 1
 			var exist bool
 
-			if m.Captures[1] == "" && m.Captures[3] == "" {
+			if m.Captures[0] == "" && m.Captures[2] == "" && m.Captures[4] == "" {
 				return false, nil
 			}
 
-			if m.Captures[0] != "" {
-				monInt, exist = MON_WORDS[compressStr(m.Captures[0])]
+			if m.Captures[2] != "" {
+				monInt, exist = MON_WORDS[compressStr(m.Captures[2])]
 				if !exist {
-					mon, err := strconv.Atoi(m.Captures[0])
+					mon, err := strconv.Atoi(m.Captures[2])
 					if err != nil {
 						return false, nil
 					}
@@ -53,10 +57,10 @@ func ExactMonthDate(s rules.Strategy) rules.Rule {
 				}
 			}
 
-			if m.Captures[2] != "" {
-				dayInt, exist = DAY_WORDS[compressStr(m.Captures[2])]
+			if m.Captures[4] != "" {
+				dayInt, exist = DAY_WORDS[compressStr(m.Captures[4])]
 				if !exist {
-					day, err := strconv.Atoi(m.Captures[2])
+					day, err := strconv.Atoi(m.Captures[4])
 					if err != nil {
 						return false, nil
 					}
@@ -64,6 +68,19 @@ func ExactMonthDate(s rules.Strategy) rules.Rule {
 				}
 			}
 
+			if m.Captures[0] != "" && m.Captures[1] != "" {
+				mon, err := strconv.Atoi(m.Captures[0])
+				if err != nil {
+					return false, nil
+				}
+				day, err := strconv.Atoi(m.Captures[1])
+				if err != nil {
+					return false, nil
+				}
+				monInt = mon
+				dayInt = day
+			}
+
 			c.Month = &monInt
 			c.Day = &dayInt
 
diff --git a/rules/zh/weekday_test.go b/rules/zh/weekday_test.go
index e8718a2..b301808 100644
--- a/rules/zh/weekday_test.go
+++ b/rules/zh/weekday_test.go
@@ -1,12 +1,12 @@
 package zh_test
 
 import (
-	"github.com/olebedev/when/rules/zh"
 	"testing"
 	"time"
 
 	"github.com/olebedev/when"
 	"github.com/olebedev/when/rules"
+	"github.com/olebedev/when/rules/zh"
 )
 
 func TestWeekday(t *testing.T) {