1 files changed, 101 insertions, 0 deletions
diff --git a/src/source-map.h b/src/source-map.h
new file mode 100644
index 000000000..d8c50b5e1
--- /dev/null
+++ b/src/source-map.h
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2024 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_source_map_h
+#define wasm_source_map_h
+
+#include <optional>
+#include <unordered_map>
+
+#include "wasm.h"
+
+namespace wasm {
+
+struct MapParseException {
+  std::string text;
+
+  MapParseException(std::string text) : text(text) {}
+  void dump(std::ostream& o) const;
+};
+
+class SourceMapReader {
+  const std::vector<char>& buffer;
+
+  // Current position in the source map buffer.
+  size_t pos = 0;
+
+  // The location in the binary the next debug location will correspond to. 0
+  // iff there are no more debug locations.
+  size_t location = 0;
+
+  // The file index, line, column, and symbol index the next debug location will
+  // be offset from.
+  uint32_t file = 0;
+  uint32_t line = 1;
+  uint32_t col = 0;
+  uint32_t symbol = 0;
+
+  // Whether the last read record had position and symbol information.
+  bool hasInfo = false;
+  bool hasSymbol = false;
+
+public:
+  SourceMapReader(const std::vector<char>& buffer) : buffer(buffer) {}
+
+  void readHeader(Module& wasm);
+
+  std::optional<Function::DebugLocation>
+  readDebugLocationAt(size_t currLocation);
+
+  // Do not reuse debug info across function boundaries.
+  void finishFunction() { hasInfo = false; }
+
+private:
+  char peek() {
+    if (pos >= buffer.size()) {
+      throw MapParseException("unexpected end of source map");
+    }
+    return buffer[pos];
+  }
+
+  char get() {
+    char c = peek();
+    ++pos;
+    return c;
+  }
+
+  bool maybeGet(char c) {
+    if (pos < buffer.size() && peek() == c) {
+      ++pos;
+      return true;
+    }
+    return false;
+  }
+
+  void expect(char c) {
+    using namespace std::string_literals;
+    char got = get();
+    if (got != c) {
+      throw MapParseException("expected '"s + c + "', got '" + got + "'");
+    }
+  }
+
+  int32_t readBase64VLQ();
+};
+
+} // namespace wasm
+
+#endif // wasm_source_map_h