diff options
| -rw-r--r-- | util/dbuffer.lua | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/util/dbuffer.lua b/util/dbuffer.lua index 9d58b306..640c1449 100644 --- a/util/dbuffer.lua +++ b/util/dbuffer.lua @@ -1,5 +1,6 @@ local queue = require "util.queue"; +local s_byte, s_sub = string.byte, string.sub; local dbuffer_methods = {}; local dynamic_buffer_mt = { __index = dbuffer_methods }; @@ -101,7 +102,11 @@ function dbuffer_methods:discard(requested_bytes) return true; end -function dbuffer_methods:sub(i, j) +-- Normalize i, j into absolute offsets within the +-- front chunk (accounting for front_consumed), and +-- ensure there is enough data in the first chunk +-- to cover any subsequent :sub() or :byte() operation +function dbuffer_methods:_prep_sub(i, j) if j == nil then j = -1; end @@ -118,18 +123,35 @@ function dbuffer_methods:sub(i, j) j = self._length; end if i > j then - return ""; + return nil; end self:collapse(j); - return self.items:peek():sub(self.front_consumed+1):sub(i, j); + if self.front_consumed > 0 then + i = i + self.front_consumed; + j = j + self.front_consumed; + end + + return i, j; +end + +function dbuffer_methods:sub(i, j) + i, j = self:_prep_sub(i, j); + if not i then + return ""; + end + return s_sub(self.items:peek(), i, j); end function dbuffer_methods:byte(i, j) i = i or 1; j = j or i; - return string.byte(self:sub(i, j), 1, -1); + i, j = self:_prep_sub(i, j); + if not i then + return; + end + return s_byte(self.items:peek(), i, j); end function dbuffer_methods:length() |