feat: add text/textvars for cutting preceding character when var is empty

net/smsgw/smstmpl/smstmpl.go

@@ -1,76 +0,0 @@
-package smstmpl
-
-import (
-	"fmt"
-	"maps"
-	"regexp"
-	"slices"
-	"strings"
-
-	"github.com/therootcompany/golib/net/smsgw/smscsv"
-)
-
-var reUnmatchedVars = regexp.MustCompile(`(\{[^}]+\})`)
-
-func RenderAll(messages []smscsv.Message) ([]smscsv.Message, error) {
-	for i, message := range messages {
-		rowIndex := i + 1
-
-		message.SetText(ReplaceVar(message.Template(), "Name", message.Name()))
-		keyIter := maps.Keys(message.Vars)
-		keys := slices.Sorted(keyIter)
-		for _, key := range keys {
-			val := message.Vars[key]
-			message.SetText(ReplaceVar(message.Text(), key, val))
-		}
-
-		if tmpls := reUnmatchedVars.FindAllString(message.Text(), -1); len(tmpls) != 0 {
-			return nil, &smscsv.CSVWarn{
-				Index: rowIndex,
-				Code:  "UnmatchedVars",
-				Message: fmt.Sprintf(
-					"failing due to row %d (%s): leftover template variable(s): %s",
-					rowIndex, message.Name(), strings.Join(tmpls, " "),
-				),
-				// Record: rec,
-			}
-		}
-
-		messages[i] = message
-	}
-
-	// TODO XXX AJ makes sure the copy retains its Text
-	return messages, nil
-}
-
-func ReplaceVar(text, key, val string) string {
-	if val != "" {
-		// No special treatment:
-		// "Hey {+Name}," => "Hey Doe,"
-		// "Bob,{Name}" => "Bob,Doe"
-		// "{Name-},Joe" => "Doe,Joe"
-		// "Hi {-Name-}, Joe" => "Hi Doe, Joe"
-		var reHasVar = regexp.MustCompile(fmt.Sprintf(`\{\+?%s-?\}`, regexp.QuoteMeta(key)))
-		return reHasVar.ReplaceAllString(text, val)
-	}
-
-	var metaKey = regexp.QuoteMeta(key)
-
-	// "Hey {+Name}," => "Hey ,"
-	var reEatNone = regexp.MustCompile(fmt.Sprintf(`\{\+%s\}`, metaKey))
-	text = reEatNone.ReplaceAllString(text, val)
-
-	// "Bob,{Name};" => "Bob;"
-	var reEatOneLeft = regexp.MustCompile(fmt.Sprintf(`.?\{%s\}`, metaKey))
-	text = reEatOneLeft.ReplaceAllString(text, val)
-
-	// ",{Name-};Joe" => ",Joe"
-	var reEatOneRight = regexp.MustCompile(fmt.Sprintf(`\{%s-\}.?`, metaKey))
-	text = reEatOneRight.ReplaceAllString(text, val)
-
-	// "Hi {-Name-}, Joe" => "Hi Joe"
-	var reEatOneBoth = regexp.MustCompile(fmt.Sprintf(`.?\{-%s-\}.?`, metaKey))
-	text = reEatOneBoth.ReplaceAllString(text, val)
-
-	return text
-}

text/textvars/README.md

@@ -0,0 +1,66 @@
+# [textvars](https://github.com/therootcompany/golib/tree/main/text/textvars)
+
+[![Go Reference](https://pkg.go.dev/badge/github.com/therootcompany/golib/text/textvars.svg)](https://pkg.go.dev/github.com/therootcompany/golib/text/textvars)
+
+Text replacement functions that handle the empty string / trailing comma problem in a sane way: \
+(cuts the character to the left when empty)
+
+Example: Leading space:
+
+```go
+textvars.ReplaceVar(`Hey {Name}!`, "Name", "Joe")
+// "Hey Joe!"
+
+textvars.ReplaceVar(`Hey {Name}!`, "Name", "")
+// "Hey!" 👍
+
+strings.ReplaceAll(`Hey {Name}!`, "{Name}", "")
+// "Hey !" 🫤
+```
+
+Example: Leading comma:
+
+```go
+textvars.ReplaceVar(`Apples,{Fruit},Bananas`, "Fruit", "Oranges")
+// "Apples,Oranges,Bananas"
+
+textvars.ReplaceVar(`Apples,{Fruit},Bananas`, "Fruit", "")
+// "Apples,Bananas" 👍
+
+strings.ReplaceAll(`Apples,{Fruit},Bananas`, "{Fruit}", "")
+// "Apples,,Bananas" 🫤
+```
+
+Example: Multiple Vars
+
+```go
+tmpl := `{#}. {Name}`
+vars := map[string]string{
+    "#": "1",
+    "Name": "Joe",
+}
+text, err := textvars.ReplaceVars(tmpl, vars)
+// "1. Joe"
+// errors if any {...} are left over
+```
+
+**Note**: This is the sort of thing that's it's probably better to copy and paste rather than to have as a dependency, but I wanted to have it for myself as a convenience in my own repo of tools, so here it is.
+
+## Other Uses
+
+It seemed like an okay idea at the time, so I also baked in some other uses:
+
+| Syntax     | Example        | "Joe"       | Empty ("") | Comment                       |
+| ---------- | -------------- | ----------- | ---------- | ----------------------------- |
+| `{Name}`   | `Hey {Name}!`  | `Hey Joe!`  | `Hey!`     | cuts left character if empty  |
+| `{Name-}`  | `1,{Name-},3`  | `1,Joe,3`   | `1,3`      | cuts right character if empty |
+| `{-Name-}` | `Hey! {Name}!` | `Hey! Joe!` | `Hey!`     | cuts left and right if empty  |
+| `{+Name}`  | `Name:{+Name}` | `Name:Joe`  | `Name:`    | keeps left character always   |
+
+However, I haven't actually had the use case for those yet and you probably won't either... so don't use what you don't need. 🙃
+
+I DO NOT plan on making a robust template system. I was only interested in solving the _leading space_ / _trailing comma_ problem for [sendsms](https://github.com/therootcompany/golib/tree/main/cmd/sendsms).
+
+# Legal
+
+CC0-1.0 (Public Domain)

text/textvars/go.mod

@@ -0,0 +1,3 @@
+module github.com/therootcompany/golib/text/textvars
+
+go 1.25.4

text/textvars/textvars.go

@@ -0,0 +1,72 @@
+// Authored in 2026 by AJ ONeal <aj@therootcompany.com> (https://therootcompany.com)
+//
+// To the extent possible under law, the author(s) have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication along with
+// this software. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
+//
+// SPDX-License-Identifier: CC0-1.0
+
+package textvars
+
+import (
+	"fmt"
+	"maps"
+	"regexp"
+	"slices"
+	"strings"
+)
+
+var reUnmatchedVars = regexp.MustCompile(`(\{[^}]+\})`)
+
+func GetPlaceholders(tmpl string) []string {
+	return reUnmatchedVars.FindAllString(tmpl, -1)
+}
+
+func ReplaceVars(text string, vars map[string]string) (string, error) {
+	keyIter := maps.Keys(vars)
+	keys := slices.Sorted(keyIter)
+	for _, key := range keys {
+		val := vars[key]
+		text = ReplaceVar(text, key, val)
+	}
+
+	if tmpls := GetPlaceholders(text); len(tmpls) != 0 {
+		return "", fmt.Errorf("leftover template variable(s): %s", strings.Join(tmpls, " "))
+	}
+
+	return text, nil
+}
+
+func ReplaceVar(text, key, val string) string {
+	if val != "" {
+		// No special treatment:
+		// "Hey {+Name}," => "Hey Doe,"
+		// "Bob,{Name}" => "Bob,Doe"
+		// "{Name-},Joe" => "Doe,Joe"
+		// "Hi {-Name-}, Joe" => "Hi Doe, Joe"
+		var reHasVar = regexp.MustCompile(fmt.Sprintf(`\{\+?%s-?\}`, regexp.QuoteMeta(key)))
+		return reHasVar.ReplaceAllString(text, val)
+	}
+
+	var metaKey = regexp.QuoteMeta(key)
+
+	// "Hey {+Name}," => "Hey ,"
+	text = strings.ReplaceAll(text, `{+`+key+`}`, val)
+
+	// "Bob,{Name};" => "Bob;"
+	var reEatOneLeft = regexp.MustCompile(fmt.Sprintf(`.?\{%s\}`, metaKey))
+	text = reEatOneLeft.ReplaceAllString(text, val)
+
+	// ",{Name-};Joe" => ",Joe"
+	var reEatOneRight = regexp.MustCompile(fmt.Sprintf(`\{%s-\}.?`, metaKey))
+	text = reEatOneRight.ReplaceAllString(text, val)
+
+	// "Hi {-Name-}, Joe" => "Hi Joe"
+	var reEatOneBoth = regexp.MustCompile(fmt.Sprintf(`.?\{-%s-\}.?`, metaKey))
+	text = reEatOneBoth.ReplaceAllString(text, val)
+
+	return text
+}