From 2546e12708a4def41cfbb36f35666ca2d702b8c7 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Tue, 7 Feb 2023 15:20:44 +1300
Subject: [PATCH] Implement more typeclasses & ensure empty input don't throw
 errors.

---
 Data/Text/Glyphize.hs        |  2 ++
 Data/Text/Glyphize/Buffer.hs |  1 +
 Data/Text/Glyphize/Font.hs   | 12 ++++++------
 harfbuzz-pure.cabal          |  2 +-
 4 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/Data/Text/Glyphize.hs b/Data/Text/Glyphize.hs
index 70ee22a..ec84b09 100644
--- a/Data/Text/Glyphize.hs
+++ b/Data/Text/Glyphize.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 -- | HarfBuzz is a text shaping library.
 -- Using the HarfBuzz library allows programs to convert a sequence of
 -- Unicode input into properly formatted and positioned glyph output —
@@ -46,6 +47,7 @@ import Foreign.Marshal.Array (withArrayLen)
 -- If two `Feature`s have the same tag but overlapping ranges
 -- the value of the `Feature` with the higher index takes precedance.
 shape :: Font -> Buffer -> [Feature] -> [(GlyphInfo, GlyphPos)]
+shape _ Buffer {text = ""} _ = []
 shape font buffer features = unsafePerformIO $ withForeignPtr font $ \font' ->
     withBuffer buffer $ \buffer' -> withArrayLen features $ \len features' -> do
         hb_shape font' buffer' features' $ toEnum len
diff --git a/Data/Text/Glyphize/Buffer.hs b/Data/Text/Glyphize/Buffer.hs
index 27e7681..2c43d09 100644
--- a/Data/Text/Glyphize/Buffer.hs
+++ b/Data/Text/Glyphize/Buffer.hs
@@ -323,6 +323,7 @@ withBuffer buf cb = withNewBuffer $ \buf' -> bufferWithText buf' (text buf) $ do
         (Just ContentTypeUnicode, Nothing, _, _) -> hb_buffer_guess_segment_properties buf'
         (Just ContentTypeUnicode, _, Nothing, _) -> hb_buffer_guess_segment_properties buf'
         (Just ContentTypeUnicode, _, _, Nothing) -> hb_buffer_guess_segment_properties buf'
+        _ -> return ()
 
     throwFalse $ hb_buffer_allocation_successful buf'
     cb buf'
diff --git a/Data/Text/Glyphize/Font.hs b/Data/Text/Glyphize/Font.hs
index 8395ee9..211f8e3 100644
--- a/Data/Text/Glyphize/Font.hs
+++ b/Data/Text/Glyphize/Font.hs
@@ -44,7 +44,7 @@ data Feature = Feature {
     -- ^ The cluster to start applying this feature setting (inclusive).
     featEnd :: Word
     -- ^ The cluster to end applying this feature setting (exclusive).
-} deriving (Read, Show, Generic)
+} deriving (Read, Show, Generic, Ord, Eq)
 instance GStorable Feature
 -- | Parses a string into a hb_feature_t.
 -- The format for specifying feature strings follows. All valid CSS
@@ -80,7 +80,7 @@ data Variation = Variation {
     -- ^ Tag of the variation-axis name. Use `varTag` to decode as an ASCII string.
     varValue :: Float
     -- ^ Value of the variation axis.
-} deriving (Read, Show, Generic)
+} deriving (Read, Show, Generic, Ord, Eq)
 instance GStorable Variation
 -- | Parses a string into a hb_variation_t.
 -- The format for specifying variation settings follows.
@@ -238,7 +238,7 @@ data FaceOptions = FaceOptions {
     faceOptUPEm :: Maybe Word
     -- ^ Sets the units-per-em (upem) for a newly-created `Face` object
     -- to the specified value.
-}
+} deriving (Read, Show, Ord, Eq)
 -- | `FaceOptions` which has no effect on the newly-created `Face` object.
 defaultFaceOptions = FaceOptions Nothing Nothing Nothing
 -- | Internal utility to apply the given `FaceOptions` to a `Face`.
@@ -451,7 +451,7 @@ data GlyphExtents = GlyphExtents {
     -- ^ Distance from the left extremum of the glyph to the right extremum.
     height :: Word32
     -- ^ Distance from the top extremum of the glyph to the right extremum.
-} deriving (Generic)
+} deriving (Generic, Read, Show, Ord, Eq)
 instance GStorable GlyphExtents
 -- | Fetches the `GlyphExtents` data for a glyph ID in the specified `Font`.
 fontGlyphExtents :: Font -> Word32 -> Maybe GlyphExtents
@@ -754,7 +754,7 @@ data FontExtents = FontExtents {
     -- ^ The depth of typographic descenders.
     lineGap :: Int32
     -- ^ The suggested line-spacing gap.
-} deriving (Generic)
+} deriving (Generic, Read, Show, Ord, Eq)
 instance GStorable FontExtents
 -- | Fetches the extents for a font in a text segment of the specified direction.
 -- Calls the appropriate direction-specific variant (horizontal or vertical)
@@ -831,7 +831,7 @@ data FontOptions = FontOptions {
     -- Axes not included in coords will be effectively set to their default values.
     optionVarNamedInstance :: Maybe Word
     -- ^ Sets design coords of a font from a named instance index.
-}
+} deriving (Show, Ord, Eq)
 -- | `FontOptions` which has no effect on the newly-created `Font`.
 defaultFontOptions = FontOptions {
     optionPPEm = Nothing, optionPtEm = Nothing, optionScale = Nothing,
diff --git a/harfbuzz-pure.cabal b/harfbuzz-pure.cabal
index ab611a3..3e41e7a 100644
--- a/harfbuzz-pure.cabal
+++ b/harfbuzz-pure.cabal
@@ -10,7 +10,7 @@ name:                harfbuzz-pure
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             1.0.1.0
+version:             1.0.2.0
 
 -- A short (one-line) description of the package.
 synopsis:            Pure-functional Harfbuzz language bindings
-- 
2.30.2