1 files changed, 96 insertions, 0 deletions
diff --git a/libbpkg/buildfile-scanner.hxx b/libbpkg/buildfile-scanner.hxx
new file mode 100644
index 0000000..8b5f0d7
--- /dev/null
+++ b/libbpkg/buildfile-scanner.hxx
@@ -0,0 +1,96 @@
+// file      : libbpkg/buildfile-scanner.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBPKG_BUILDFILE_SCANNER_HXX
+#define LIBBPKG_BUILDFILE_SCANNER_HXX
+
+#include <string>
+#include <cstdint>   // uint64_t
+#include <cstddef>   // size_t
+#include <stdexcept> // runtime_error
+
+#include <libbutl/char-scanner.hxx>
+
+#include <libbpkg/export.hxx>
+
+namespace bpkg
+{
+  // Scan buildfile fragments, respecting the single- and double-quoted
+  // character sequences, backslash-escaping, comments, evaluation
+  // contexts, and nested blocks.
+  //
+  class LIBBPKG_EXPORT buildfile_scanning: public std::runtime_error
+  {
+  public:
+    buildfile_scanning (const std::string& name,
+                        std::uint64_t line,
+                        std::uint64_t column,
+                        const std::string& description);
+
+    std::string name;
+    std::uint64_t line;
+    std::uint64_t column;
+    std::string description;
+  };
+
+  template <typename V, std::size_t N>
+  class buildfile_scanner
+  {
+  public:
+    // Note that name is stored by shallow reference.
+    //
+    buildfile_scanner (butl::char_scanner<V, N>& s, const std::string& name)
+        : scan_ (s), name_ (name) {}
+
+    // Scan the buildfile line and return the scanned fragment. Optionally,
+    // specify an additional stop character. Leave the newline (or the stop
+    // character) in the stream. Throw buildfile_scanning on error
+    // (unterminated quoted sequence, etc).
+    //
+    std::string
+    scan_line (char stop = '\0');
+
+    // Scan the buildfile line until an unbalanced ')' character is encountered
+    // and return the scanned fragment, leaving ')' in the stream. Throw
+    // buildfile_scanning on error or if eos or newline is reached.
+    //
+    std::string
+    scan_eval ();
+
+    // Scan the buildfile block until an unbalanced block closing '}' character
+    // is encountered and return the scanned fragment. Throw buildfile_scanning
+    // on error or if eos is reached.
+    //
+    // Note that the block opening '{' and closing '}' characters are only
+    // considered as such, if they are the only characters on the line besides
+    // whitespaces and comments. Also note that the fragment terminating '}'
+    // line is consumed from the stream but is not included into the fragment.
+    //
+    std::string
+    scan_block ();
+
+  private:
+    using scanner = butl::char_scanner<V, N>;
+    using xchar = typename scanner::xchar;
+
+    xchar
+    peek ();
+
+    // Scan the buildfile line, saving the scanned characters into the
+    // specified string, leaving newline and the stop character, if specified,
+    // in the stream. Return '{' if this line is a block-opening curly brace,
+    // '}' if it is a block-closing curly brace, and '\0' otherwise.
+    //
+    char
+    scan_line (std::string& l, char stop = '\0');
+
+  private:
+    scanner&           scan_;
+    const std::string& name_;
+    std::string        ebuf_; // Error message buffer.
+  };
+}
+
+#include <libbpkg/buildfile-scanner.txx>
+
+#endif // LIBBPKG_BUILDFILE_SCANNER_HXX