Vendor things

third-party/vendor/ttf-parser-0.15.2/src/tables/cmap/format6.rs

@@ -0,0 +1,47 @@
+use core::convert::TryFrom;
+
+use crate::parser::{LazyArray16, Stream};
+use crate::GlyphId;
+
+/// A [format 6](https://docs.microsoft.com/en-us/typography/opentype/spec/cmap#format-6-trimmed-table-mapping)
+/// subtable.
+#[derive(Clone, Copy, Debug)]
+pub struct Subtable6<'a> {
+    /// First character code of subrange.
+    pub first_code_point: u16,
+    /// Array of glyph indexes for character codes in the range.
+    pub glyphs: LazyArray16<'a, GlyphId>,
+}
+
+impl<'a> Subtable6<'a> {
+    /// Parses a subtable from raw data.
+    pub fn parse(data: &'a [u8]) -> Option<Self> {
+        let mut s = Stream::new(data);
+        s.skip::<u16>(); // format
+        s.skip::<u16>(); // length
+        s.skip::<u16>(); // language
+        let first_code_point = s.read::<u16>()?;
+        let count = s.read::<u16>()?;
+        let glyphs = s.read_array16::<GlyphId>(count)?;
+        Some(Self { first_code_point, glyphs })
+    }
+
+    /// Returns a glyph index for a code point.
+    ///
+    /// Returns `None` when `code_point` is larger than `u16`.
+    pub fn glyph_index(&self, code_point: u32) -> Option<GlyphId> {
+        // This subtable supports code points only in a u16 range.
+        let code_point = u16::try_from(code_point).ok()?;
+        let idx = code_point.checked_sub(self.first_code_point)?;
+        self.glyphs.get(idx)
+    }
+
+    /// Calls `f` for each codepoint defined in this table.
+    pub fn codepoints(&self, mut f: impl FnMut(u32)) {
+        for i in 0..self.glyphs.len() {
+            if let Some(code_point) = self.first_code_point.checked_add(i) {
+                f(u32::from(code_point));
+            }
+        }
+    }
+}