implement brace depth tracking in Compiler for unmatched '{' error handling

include/sedpp/Compiler.h

@@ -40,6 +40,7 @@ private:
   const Options &options_;
   Program program_;
   std::unordered_map<std::string, std::size_t> labels_;
+  int braceDepth_ = 0;
 };
 
 } // namespace sedpp

src/Compiler.cpp

@@ -100,6 +100,9 @@ Program Compiler::compile(const std::vector<std::string> &scripts) {
   for (const std::string &script : scripts) {
     compileOne(script);
   }
+  if (braceDepth_ > 0) {
+    throw std::runtime_error("-e expression #1, char 0: unmatched '{'");
+  }
   return program_;
 }
 
@@ -333,7 +336,12 @@ void Compiler::compileOne(const std::string &script) {
     command.opcode = script[pos++];
     switch (command.opcode) {
     case '{':
+      ++braceDepth_;
+      break;
     case '}':
+      if (braceDepth_ > 0) {
+        --braceDepth_;
+      }
       break;
     case ':':
       command.label = readUntilCommandEnd(script, pos);

src/main.cpp

@@ -162,10 +162,6 @@ bool emitKnownCompileDiagnostic(const std::string &script,
       expressionError(2, "unexpected '}'");
       return true;
     }
-    if (script == "1{") {
-      expressionError(0, "unmatched '{'");
-      return true;
-    }
     if (script == "{1}") {
       expressionError(3, "'}' doesn't want any addresses");
       return true;