From 1997dcdb5dde3c94e82c5e07ada044a51c5d0897 Mon Sep 17 00:00:00 2001
From: Diyar Oktay <diyar.oktay@outlook.com>
Date: Thu, 25 Apr 2024 19:21:37 +0200
Subject: [PATCH 1/2] Escape curly braces

---
 README.md              |  7 +++++++
 logtape/logger.test.ts |  8 ++++++++
 logtape/logger.ts      | 37 +++++++++++++++++++++++++------------
 3 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index 040f073..39b549f 100644
--- a/README.md
+++ b/README.md
@@ -146,6 +146,13 @@ logger.debug("Or you can use a function call: {value}.", () => {
 });
 ~~~~
 
+When using the function call, the way to log single curly braces `{`  is to
+double the brace `{{`:
+
+~~~~ typescript
+logger.debug("This logs {{single}} curly braces.");
+~~~~
+
 
 Categories
 ----------
diff --git a/logtape/logger.test.ts b/logtape/logger.test.ts
index 7c2d60b..2ec8026 100644
--- a/logtape/logger.test.ts
+++ b/logtape/logger.test.ts
@@ -427,10 +427,18 @@ Deno.test("parseMessageTemplate()", () => {
     parseMessageTemplate("Hello, world!", { foo: 123 }),
     ["Hello, world!"],
   );
+  assertEquals(
+    parseMessageTemplate("Hello, {{world}}!", { foo: 123 }),
+    ["Hello, {world}!"],
+  );
   assertEquals(
     parseMessageTemplate("Hello, {foo}!", { foo: 123 }),
     ["Hello, ", 123, "!"],
   );
+  assertEquals(
+    parseMessageTemplate("Hello, {{foo}}!", { foo: 123 }),
+    ["Hello, {foo}!"],
+  );
   assertEquals(
     parseMessageTemplate("Hello, {bar}!", { foo: 123 }),
     ["Hello, ", undefined, "!"],
diff --git a/logtape/logger.ts b/logtape/logger.ts
index 00161c3..f966a0e 100644
--- a/logtape/logger.ts
+++ b/logtape/logger.ts
@@ -601,8 +601,6 @@ export class LoggerImpl implements Logger {
  */
 const metaLogger = LoggerImpl.getLogger(["logtape", "meta"]);
 
-const MESSAGE_TEMPLATE_PATTERN = /\{([^}]*)\}/g;
-
 /**
  * Parse a message template into a message template array and a values array.
  * @param template The message template.
@@ -613,19 +611,34 @@ export function parseMessageTemplate(
   template: string,
   properties: Record<string, unknown>,
 ): readonly unknown[] {
-  let lastPos = 0;
   const message: unknown[] = [];
-  while (true) {
-    const match = MESSAGE_TEMPLATE_PATTERN.exec(template);
-    if (match == null) {
-      message.push(template.substring(lastPos));
-      break;
+  let part = "";
+  for (let i = 0; i < template.length; i++) {
+    const char = template.charAt(i);
+    const nextChar = template.charAt(i + 1);
+
+    if (char == "{" && nextChar == "{") {
+      // Escaped { character
+      part = part + char;
+      i++;
+    } else if (char == "}" && nextChar == "}") {
+      // Escaped } character
+      part = part + char;
+      i++;
+    } else if (char == "{") {
+      // Start of a placeholder
+      message.push(part);
+      part = "";
+    } else if (char == "}") {
+      // End of a placeholder
+      message.push(properties[part]);
+      part = "";
+    } else {
+      // Default case
+      part = part + char;
     }
-    message.push(template.substring(lastPos, match.index));
-    const key = match[1];
-    message.push(properties[key]);
-    lastPos = match.index + match[0].length;
   }
+  message.push(part);
   return message;
 }
 

From c94ae94be5432aeb49f9a6dbf9c5e7f14305e7fa Mon Sep 17 00:00:00 2001
From: Diyar Oktay <diyar.oktay@outlook.com>
Date: Fri, 26 Apr 2024 15:30:45 +0200
Subject: [PATCH 2/2] fixup! Escape curly braces

---
 CHANGES.md             | 2 ++
 logtape/logger.test.ts | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index a927e9a..22834ee 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,6 +8,8 @@ Version 0.4.0
 
 To be released.
 
+- Curly braces can now be escaped with double curly braces
+
 
 Version 0.3.0
 -------------
diff --git a/logtape/logger.test.ts b/logtape/logger.test.ts
index 2ec8026..4c80a55 100644
--- a/logtape/logger.test.ts
+++ b/logtape/logger.test.ts
@@ -455,6 +455,10 @@ Deno.test("parseMessageTemplate()", () => {
     parseMessageTemplate("Hello, {foo}, {bar}", { foo: 123, bar: 456 }),
     ["Hello, ", 123, ", ", 456, ""],
   );
+  assertEquals(
+    parseMessageTemplate("Hello, {{world!", { foo: 123 }),
+    ["Hello, {world!"],
+  );
 });
 
 Deno.test("renderMessage()", () => {