Add LineEndings module.

src/jes/core/lineendings.d

@@ -0,0 +1,61 @@
+module jes.core.lineendings;
+
+struct LineEndings
+{
+    enum : ubyte
+    {
+        LF,
+        CRLF,
+    }
+
+    ubyte type;
+    alias type this;
+
+    this(ubyte type)
+    {
+        this.type = type;
+    }
+
+    static LineEndings detect_line_endings(const ubyte * data, size_t n)
+    {
+        size_t lf_count = 0u;
+        for (size_t i = 0u; i < n; i++)
+        {
+            if (data[i] == '\n')
+            {
+                lf_count++;
+                /* Every LF must be preceded by a CR for the content to have
+                 * CRLF line endings. */
+                if ((i == 0u) || (data[i - 1u] != '\r'))
+                {
+                    return LineEndings(LF);
+                }
+            }
+        }
+        if (lf_count > 0u)
+        {
+            return LineEndings(CRLF);
+        }
+        return LineEndings(LF);
+    }
+
+    unittest
+    {
+        import std.stdio;
+        import std.file;
+        const(ubyte)[] dat;
+        LineEndings le;
+
+        dat = cast(const(ubyte)[])std.file.read("test/files/line_endings/crlf_format.txt");
+        le = LineEndings.detect_line_endings(dat.ptr, dat.length);
+        assert(le == LineEndings.CRLF);
+
+        dat = cast(const(ubyte)[])std.file.read("test/files/empty.txt");
+        le = LineEndings.detect_line_endings(dat.ptr, 0u);
+        assert(le == LineEndings.LF);
+
+        dat = cast(const(ubyte)[])std.file.read("test/files/line_endings/lf_format.txt");
+        le = LineEndings.detect_line_endings(dat.ptr, dat.length);
+        assert(le == LineEndings.LF);
+    }
+}

test/files/line_endings/cr_format.txt

@@ -1 +0,0 @@
-Hello.
This file is in CR line ending format.