1 files changed, 61 insertions, 0 deletions
diff --git a/prism/line_offset_list.h b/prism/line_offset_list.h
new file mode 100644
index 0000000000..848bc49139
--- /dev/null
+++ b/prism/line_offset_list.h
@@ -0,0 +1,61 @@
+/**
+ * @file line_offset_list.h
+ *
+ * A list of byte offsets of newlines in a string.
+ *
+ * When compiling the syntax tree, it's necessary to know the line and column
+ * of many nodes. This is necessary to support things like error messages,
+ * tracepoints, etc.
+ *
+ * It's possible that we could store the start line, start column, end line, and
+ * end column on every node in addition to the offsets that we already store,
+ * but that would be quite a lot of memory overhead.
+ */
+#ifndef PRISM_LINE_OFFSET_LIST_H
+#define PRISM_LINE_OFFSET_LIST_H
+
+#include "prism/compiler/exported.h"
+#include "prism/compiler/nonnull.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+/**
+ * A list of offsets of the start of lines in a string. The offsets are assumed
+ * to be sorted/inserted in ascending order.
+ */
+typedef struct {
+    /** The number of offsets in the list. */
+    size_t size;
+
+    /** The capacity of the list that has been allocated. */
+    size_t capacity;
+
+    /** The list of offsets. */
+    uint32_t *offsets;
+} pm_line_offset_list_t;
+
+/**
+ * A line and column in a string.
+ */
+typedef struct {
+    /** The line number. */
+    int32_t line;
+
+    /** The column in bytes. */
+    uint32_t column;
+} pm_line_column_t;
+
+/**
+ * Returns the line and column of the given offset. If the offset is not in the
+ * list, the line and column of the closest offset less than the given offset
+ * are returned.
+ *
+ * @param list The list to search.
+ * @param cursor The offset to search for.
+ * @param start_line The line to start counting from.
+ * @returns The line and column of the given offset.
+ */
+PRISM_EXPORTED_FUNCTION pm_line_column_t pm_line_offset_list_line_column(const pm_line_offset_list_t *list, uint32_t cursor, int32_t start_line) PRISM_NONNULL(1);
+
+#endif