| Copyright | (c) 2013 Bryan O'Sullivan (c) 2010 Johan Tibell |
|---|---|
| License | BSD3-style (see LICENSE) |
| Maintainer | Johan Tibell <johan.tibell@gmail.com> |
| Stability | experimental |
| Portability | portable to Hugs and GHC |
| Safe Haskell | None |
| Language | Haskell98 |
Data.Text.Internal.Builder
Description
Warning: this is an internal module, and does not have a stable API or name. Functions in this module may not check or enforce preconditions expected by public modules. Use at your own risk!
Efficient construction of lazy Text values. The principal
operations on a Builder are singleton, fromText, and
fromLazyText, which construct new builders, and mappend, which
concatenates two builders.
To get maximum performance when building lazy Text values using a
builder, associate mappend calls to the right. For example,
prefer
singleton 'a' `mappend` (singleton 'b' `mappend` singleton 'c')
to
singleton 'a' `mappend` singleton 'b' `mappend` singleton 'c'
as the latter associates mappend to the left.
- data Builder
- toLazyText :: Builder -> Text
- toLazyTextWith :: Int -> Builder -> Text
- singleton :: Char -> Builder
- fromText :: Text -> Builder
- fromLazyText :: Text -> Builder
- fromString :: String -> Builder
- flush :: Builder
- append' :: Builder -> Builder -> Builder
- ensureFree :: Int -> Builder
- writeN :: Int -> (forall s. MArray s -> Int -> ST s ()) -> Builder
Public API
The Builder type
A Builder is an efficient way to build lazy Text values.
There are several functions for constructing builders, but only one
to inspect them: to extract any data, you have to turn them into
lazy Text values using toLazyText.
Internally, a builder constructs a lazy Text by filling arrays
piece by piece. As each buffer is filled, it is 'popped' off, to
become a new chunk of the resulting lazy Text. All this is
hidden from the user of the Builder.
toLazyText :: Builder -> Text Source
O(n). Extract a lazy Text from a Builder with a default
buffer size. The construction work takes place if and when the
relevant part of the lazy Text is demanded.
toLazyTextWith :: Int -> Builder -> Text Source
O(n). Extract a lazy Text from a Builder, using the given
size for the initial buffer. The construction work takes place if
and when the relevant part of the lazy Text is demanded.
If the initial buffer is too small to hold all data, subsequent buffers will be the default buffer size.
Constructing Builders
singleton :: Char -> Builder Source
O(1). A Builder taking a single character, satisfying
toLazyText(singletonc) =singletonc
fromText :: Text -> Builder Source
O(1). A Builder taking a Text, satisfying
toLazyText(fromTextt) =fromChunks[t]
fromLazyText :: Text -> Builder Source
O(1). A Builder taking a lazy Text, satisfying
toLazyText(fromLazyTextt) = t
fromString :: String -> Builder Source
O(1). A Builder taking a String, satisfying
toLazyText(fromStrings) =fromChunks[S.pack s]
Flushing the buffer state
O(1). Pop the strict Text we have constructed so far, if any,
yielding a new chunk in the result lazy Text.
Internal functions
ensureFree :: Int -> Builder Source
Ensure that there are at least n many elements available.