1 files changed, 219 insertions, 0 deletions
diff --git a/contrib/python/fonttools/fontTools/varLib/errors.py b/contrib/python/fonttools/fontTools/varLib/errors.py
new file mode 100644
index 00000000000..4f30f901bab
--- /dev/null
+++ b/contrib/python/fonttools/fontTools/varLib/errors.py
@@ -0,0 +1,219 @@
+import textwrap
+
+
+class VarLibError(Exception):
+    """Base exception for the varLib module."""
+
+
+class VarLibValidationError(VarLibError):
+    """Raised when input data is invalid from varLib's point of view."""
+
+
+class VarLibMergeError(VarLibError):
+    """Raised when input data cannot be merged into a variable font."""
+
+    def __init__(self, merger=None, **kwargs):
+        self.merger = merger
+        if not kwargs:
+            kwargs = {}
+        if "stack" in kwargs:
+            self.stack = kwargs["stack"]
+            del kwargs["stack"]
+        else:
+            self.stack = []
+        self.cause = kwargs
+
+    @property
+    def reason(self):
+        return self.__doc__
+
+    def _master_name(self, ix):
+        if self.merger is not None:
+            ttf = self.merger.ttfs[ix]
+            if "name" in ttf and ttf["name"].getBestFullName():
+                return ttf["name"].getBestFullName()
+            elif hasattr(ttf.reader, "file") and hasattr(ttf.reader.file, "name"):
+                return ttf.reader.file.name
+        return f"master number {ix}"
+
+    @property
+    def offender(self):
+        if "expected" in self.cause and "got" in self.cause:
+            index = [x == self.cause["expected"] for x in self.cause["got"]].index(
+                False
+            )
+            master_name = self._master_name(index)
+            if "location" in self.cause:
+                master_name = f"{master_name} ({self.cause['location']})"
+            return index, master_name
+        return None, None
+
+    @property
+    def details(self):
+        if "expected" in self.cause and "got" in self.cause:
+            offender_index, offender = self.offender
+            got = self.cause["got"][offender_index]
+            return f"Expected to see {self.stack[0]}=={self.cause['expected']!r}, instead saw {got!r}\n"
+        return ""
+
+    def __str__(self):
+        offender_index, offender = self.offender
+        location = ""
+        if offender:
+            location = f"\n\nThe problem is likely to be in {offender}:\n"
+        context = "".join(reversed(self.stack))
+        basic = textwrap.fill(
+            f"Couldn't merge the fonts, because {self.reason}. "
+            f"This happened while performing the following operation: {context}",
+            width=78,
+        )
+        return "\n\n" + basic + location + self.details
+
+
+class ShouldBeConstant(VarLibMergeError):
+    """some values were different, but should have been the same"""
+
+    @property
+    def details(self):
+        basic_message = super().details
+
+        if self.stack[0] != ".FeatureCount" or self.merger is None:
+            return basic_message
+
+        assert self.stack[0] == ".FeatureCount"
+        offender_index, _ = self.offender
+        bad_ttf = self.merger.ttfs[offender_index]
+        good_ttf = next(
+            ttf
+            for ttf in self.merger.ttfs
+            if self.stack[-1] in ttf
+            and ttf[self.stack[-1]].table.FeatureList.FeatureCount
+            == self.cause["expected"]
+        )
+
+        good_features = [
+            x.FeatureTag
+            for x in good_ttf[self.stack[-1]].table.FeatureList.FeatureRecord
+        ]
+        bad_features = [
+            x.FeatureTag
+            for x in bad_ttf[self.stack[-1]].table.FeatureList.FeatureRecord
+        ]
+        return basic_message + (
+            "\nIncompatible features between masters.\n"
+            f"Expected: {', '.join(good_features)}.\n"
+            f"Got: {', '.join(bad_features)}.\n"
+        )
+
+
+class FoundANone(VarLibMergeError):
+    """one of the values in a list was empty when it shouldn't have been"""
+
+    @property
+    def offender(self):
+        index = [x is None for x in self.cause["got"]].index(True)
+        return index, self._master_name(index)
+
+    @property
+    def details(self):
+        cause, stack = self.cause, self.stack
+        return f"{stack[0]}=={cause['got']}\n"
+
+
+class NotANone(VarLibMergeError):
+    """one of the values in a list was not empty when it should have been"""
+
+    @property
+    def offender(self):
+        index = [x is not None for x in self.cause["got"]].index(True)
+        return index, self._master_name(index)
+
+    @property
+    def details(self):
+        cause, stack = self.cause, self.stack
+        return f"{stack[0]}=={cause['got']}\n"
+
+
+class MismatchedTypes(VarLibMergeError):
+    """data had inconsistent types"""
+
+
+class LengthsDiffer(VarLibMergeError):
+    """a list of objects had inconsistent lengths"""
+
+
+class KeysDiffer(VarLibMergeError):
+    """a list of objects had different keys"""
+
+
+class InconsistentGlyphOrder(VarLibMergeError):
+    """the glyph order was inconsistent between masters"""
+
+
+class InconsistentExtensions(VarLibMergeError):
+    """the masters use extension lookups in inconsistent ways"""
+
+
+class UnsupportedFormat(VarLibMergeError):
+    """an OpenType subtable (%s) had a format I didn't expect"""
+
+    def __init__(self, merger=None, **kwargs):
+        super().__init__(merger, **kwargs)
+        if not self.stack:
+            self.stack = [".Format"]
+
+    @property
+    def reason(self):
+        s = self.__doc__ % self.cause["subtable"]
+        if "value" in self.cause:
+            s += f" ({self.cause['value']!r})"
+        return s
+
+
+class InconsistentFormats(UnsupportedFormat):
+    """an OpenType subtable (%s) had inconsistent formats between masters"""
+
+
+class VarLibCFFMergeError(VarLibError):
+    pass
+
+
+class VarLibCFFDictMergeError(VarLibCFFMergeError):
+    """Raised when a CFF PrivateDict cannot be merged."""
+
+    def __init__(self, key, value, values):
+        error_msg = (
+            f"For the Private Dict key '{key}', the default font value list:"
+            f"\n\t{value}\nhad a different number of values than a region font:"
+        )
+        for region_value in values:
+            error_msg += f"\n\t{region_value}"
+        self.args = (error_msg,)
+
+
+class VarLibCFFPointTypeMergeError(VarLibCFFMergeError):
+    """Raised when a CFF glyph cannot be merged because of point type differences."""
+
+    def __init__(self, point_type, pt_index, m_index, default_type, glyph_name):
+        error_msg = (
+            f"Glyph '{glyph_name}': '{point_type}' at point index {pt_index} in "
+            f"master index {m_index} differs from the default font point type "
+            f"'{default_type}'"
+        )
+        self.args = (error_msg,)
+
+
+class VarLibCFFHintTypeMergeError(VarLibCFFMergeError):
+    """Raised when a CFF glyph cannot be merged because of hint type differences."""
+
+    def __init__(self, hint_type, cmd_index, m_index, default_type, glyph_name):
+        error_msg = (
+            f"Glyph '{glyph_name}': '{hint_type}' at index {cmd_index} in "
+            f"master index {m_index} differs from the default font hint type "
+            f"'{default_type}'"
+        )
+        self.args = (error_msg,)
+
+
+class VariationModelError(VarLibError):
+    """Raised when a variation model is faulty."""