Add a line content iterator.

include/vase/buffer/append.h

@@ -27,7 +27,12 @@ struct AppendBuffer : Buffer {
   const char *read(uint32_t pos, uint32_t *out_len);
   uint32_t count_lines(uint32_t pos, uint32_t length);
 
+  uint32_t next_newline(uint32_t pos);
+  uint32_t nth_newline(uint32_t pos, uint32_t n);
+
 private:
+  inline uint32_t newline_value_at(uint32_t flat_index);
+
   inline void new_text_chunk();
   inline void new_line_chunk();
 

include/vase/buffer/buffer.h

@@ -5,6 +5,7 @@
 struct Buffer {
   virtual const char *read(uint32_t pos, uint32_t *out_len) = 0;
   virtual uint32_t count_lines(uint32_t pos, uint32_t length) = 0;
-
+  virtual uint32_t next_newline(uint32_t pos) = 0;
+  virtual uint32_t nth_newline(uint32_t pos, uint32_t n) = 0;
   virtual ~Buffer() = default;
 };

include/vase/buffer/original.h

@@ -27,4 +27,6 @@ struct OriginalBuffer : Buffer {
 
   const char *read(uint32_t pos, uint32_t *out_len);
   uint32_t count_lines(uint32_t pos, uint32_t length);
+  uint32_t next_newline(uint32_t pos);
+  uint32_t nth_newline(uint32_t pos, uint32_t n);
 };

include/vase/line_iter.h

@@ -0,0 +1,26 @@
+#pragma once
+#include "pch.h"
+#include "shard.h"
+
+struct LineIterator {
+  Shard *root = nullptr;
+  std::vector<Branch *> stack;
+  Petal *petal = nullptr;
+  uint32_t petal_offset = 0;
+
+  LineIterator(Shard *r, uint32_t start_line);
+
+  ~LineIterator();
+
+  LineIterator(const LineIterator &) = delete;
+  LineIterator &operator=(const LineIterator &) = delete;
+  LineIterator(LineIterator &&) = default;
+  LineIterator &operator=(LineIterator &&) = default;
+
+  void seek_line(uint32_t line_index);
+  bool next(std::string &line);
+
+private:
+  void descend(Shard *s);
+  bool advance_petal();
+};

include/vase/vase.h

@@ -2,6 +2,7 @@
 
 #include "buffer/append.h"
 #include "buffer/original.h"
+#include "line_iter.h"
 #include "pch.h"
 #include "shard.h"