api: implement nvim_buf_get_offset_for_line

Like line2byte, but works for any buffer, and uses zero-based
indexing (API conventions).

1 files changed, 34 insertions, 0 deletions

diff --git a/test/functional/api/buffer_spec.lua b/test/functional/api/buffer_spec.lua
index 271e196103..d3739c74d2 100644
--- a/test/functional/api/buffer_spec.lua
+++ b/test/functional/api/buffer_spec.lua
@@ -301,6 +301,40 @@ describe('api/buf', function()
     end)
   end)
 
+  describe('get_offset_for_line', function()
+    local get_offset_for_line = curbufmeths.get_offset_for_line
+    it('works', function()
+      curbufmeths.set_lines(0,-1,true,{'Some','exa\000mple', '', 'text'})
+      eq(4, curbufmeths.line_count())
+      eq(0, get_offset_for_line(0))
+      eq(5, get_offset_for_line(1))
+      eq(14, get_offset_for_line(2))
+      eq(15, get_offset_for_line(3))
+      eq(20, get_offset_for_line(4))
+      eq({false,'Index out of bounds'}, meth_pcall(get_offset_for_line, 5))
+      eq({false,'Index out of bounds'}, meth_pcall(get_offset_for_line, -1))
+
+      curbufmeths.set_option('eol', false)
+      curbufmeths.set_option('fixeol', false)
+      eq(19, get_offset_for_line(4))
+
+      curbufmeths.set_option('fileformat', 'dos')
+      eq(0, get_offset_for_line(0))
+      eq(6, get_offset_for_line(1))
+      eq(16, get_offset_for_line(2))
+      eq(18, get_offset_for_line(3))
+      eq(22, get_offset_for_line(4))
+      curbufmeths.set_option('eol', true)
+      eq(24, get_offset_for_line(4))
+
+      command("set hidden")
+      command("enew")
+      eq(6, bufmeths.get_offset_for_line(1,1))
+      command("bunload! 1")
+      eq(-1, bufmeths.get_offset_for_line(1,1))
+    end)
+  end)
+
   describe('{get,set,del}_var', function()
     it('works', function()
       curbuf('set_var', 'lua', {1, 2, {['3'] = 1}})