up follow livre

venv/lib/python3.13/site-packages/fontTools/misc/sstruct.py

@@ -0,0 +1,227 @@
+"""sstruct.py -- SuperStruct
+
+Higher level layer on top of the struct module, enabling to
+bind names to struct elements. The interface is similar to
+struct, except the objects passed and returned are not tuples
+(or argument lists), but dictionaries or instances.
+
+Just like struct, we use fmt strings to describe a data
+structure, except we use one line per element. Lines are
+separated by newlines or semi-colons. Each line contains
+either one of the special struct characters ('@', '=', '<',
+'>' or '!') or a 'name:formatchar' combo (eg. 'myFloat:f').
+Repetitions, like the struct module offers them are not useful
+in this context, except for fixed length strings  (eg. 'myInt:5h'
+is not allowed but 'myString:5s' is). The 'x' fmt character
+(pad byte) is treated as 'special', since it is by definition
+anonymous. Extra whitespace is allowed everywhere.
+
+The sstruct module offers one feature that the "normal" struct
+module doesn't: support for fixed point numbers. These are spelled
+as "n.mF", where n is the number of bits before the point, and m
+the number of bits after the point. Fixed point numbers get
+converted to floats.
+
+pack(fmt, object):
+	'object' is either a dictionary or an instance (or actually
+	anything that has a __dict__ attribute). If it is a dictionary,
+	its keys are used for names. If it is an instance, it's
+	attributes are used to grab struct elements from. Returns
+	a string containing the data.
+
+unpack(fmt, data, object=None)
+	If 'object' is omitted (or None), a new dictionary will be
+	returned. If 'object' is a dictionary, it will be used to add
+	struct elements to. If it is an instance (or in fact anything
+	that has a __dict__ attribute), an attribute will be added for
+	each struct element. In the latter two cases, 'object' itself
+	is returned.
+
+unpack2(fmt, data, object=None)
+	Convenience function. Same as unpack, except data may be longer
+	than needed. The returned value is a tuple: (object, leftoverdata).
+
+calcsize(fmt)
+	like struct.calcsize(), but uses our own fmt strings:
+	it returns the size of the data in bytes.
+"""
+
+from fontTools.misc.fixedTools import fixedToFloat as fi2fl, floatToFixed as fl2fi
+from fontTools.misc.textTools import tobytes, tostr
+import struct
+import re
+
+__version__ = "1.2"
+__copyright__ = "Copyright 1998, Just van Rossum <just@letterror.com>"
+
+
+class Error(Exception):
+    pass
+
+
+def pack(fmt, obj):
+    formatstring, names, fixes = getformat(fmt, keep_pad_byte=True)
+    elements = []
+    if not isinstance(obj, dict):
+        obj = obj.__dict__
+    for name in names.keys():
+        value = obj[name]
+        if name in fixes:
+            # fixed point conversion
+            value = fl2fi(value, fixes[name])
+        elif isinstance(value, str):
+            value = tobytes(value)
+        elements.append(value)
+        # Check it fits
+        try:
+            struct.pack(names[name], value)
+        except Exception as e:
+            raise ValueError(
+                "Value %s does not fit in format %s for %s" % (value, names[name], name)
+            ) from e
+    data = struct.pack(*(formatstring,) + tuple(elements))
+    return data
+
+
+def unpack(fmt, data, obj=None):
+    if obj is None:
+        obj = {}
+    data = tobytes(data)
+    formatstring, names, fixes = getformat(fmt)
+    if isinstance(obj, dict):
+        d = obj
+    else:
+        d = obj.__dict__
+    elements = struct.unpack(formatstring, data)
+    for i, name in enumerate(names.keys()):
+        value = elements[i]
+        if name in fixes:
+            # fixed point conversion
+            value = fi2fl(value, fixes[name])
+        elif isinstance(value, bytes):
+            try:
+                value = tostr(value)
+            except UnicodeDecodeError:
+                pass
+        d[name] = value
+    return obj
+
+
+def unpack2(fmt, data, obj=None):
+    length = calcsize(fmt)
+    return unpack(fmt, data[:length], obj), data[length:]
+
+
+def calcsize(fmt):
+    formatstring, names, fixes = getformat(fmt)
+    return struct.calcsize(formatstring)
+
+
+# matches "name:formatchar" (whitespace is allowed)
+_elementRE = re.compile(
+    r"\s*"  # whitespace
+    r"([A-Za-z_][A-Za-z_0-9]*)"  # name (python identifier)
+    r"\s*:\s*"  # whitespace : whitespace
+    r"([xcbB?hHiIlLqQfd]|"  # formatchar...
+    r"[0-9]+[ps]|"  # ...formatchar...
+    r"([0-9]+)\.([0-9]+)(F))"  # ...formatchar
+    r"\s*"  # whitespace
+    r"(#.*)?$"  # [comment] + end of string
+)
+
+# matches the special struct fmt chars and 'x' (pad byte)
+_extraRE = re.compile(r"\s*([x@=<>!])\s*(#.*)?$")
+
+# matches an "empty" string, possibly containing whitespace and/or a comment
+_emptyRE = re.compile(r"\s*(#.*)?$")
+
+_fixedpointmappings = {8: "b", 16: "h", 32: "l"}
+
+_formatcache = {}
+
+
+def getformat(fmt, keep_pad_byte=False):
+    fmt = tostr(fmt, encoding="ascii")
+    try:
+        formatstring, names, fixes = _formatcache[fmt]
+    except KeyError:
+        lines = re.split("[\n;]", fmt)
+        formatstring = ""
+        names = {}
+        fixes = {}
+        for line in lines:
+            if _emptyRE.match(line):
+                continue
+            m = _extraRE.match(line)
+            if m:
+                formatchar = m.group(1)
+                if formatchar != "x" and formatstring:
+                    raise Error("a special fmt char must be first")
+            else:
+                m = _elementRE.match(line)
+                if not m:
+                    raise Error("syntax error in fmt: '%s'" % line)
+                name = m.group(1)
+                formatchar = m.group(2)
+                if keep_pad_byte or formatchar != "x":
+                    names[name] = formatchar
+                if m.group(3):
+                    # fixed point
+                    before = int(m.group(3))
+                    after = int(m.group(4))
+                    bits = before + after
+                    if bits not in [8, 16, 32]:
+                        raise Error("fixed point must be 8, 16 or 32 bits long")
+                    formatchar = _fixedpointmappings[bits]
+                    names[name] = formatchar
+                    assert m.group(5) == "F"
+                    fixes[name] = after
+            formatstring += formatchar
+        _formatcache[fmt] = formatstring, names, fixes
+    return formatstring, names, fixes
+
+
+def _test():
+    fmt = """
+		# comments are allowed
+		>  # big endian (see documentation for struct)
+		# empty lines are allowed:
+
+		ashort: h
+		along: l
+		abyte: b	# a byte
+		achar: c
+		astr: 5s
+		afloat: f; adouble: d	# multiple "statements" are allowed
+		afixed: 16.16F
+		abool: ?
+		apad: x
+	"""
+
+    print("size:", calcsize(fmt))
+
+    class foo(object):
+        pass
+
+    i = foo()
+
+    i.ashort = 0x7FFF
+    i.along = 0x7FFFFFFF
+    i.abyte = 0x7F
+    i.achar = "a"
+    i.astr = "12345"
+    i.afloat = 0.5
+    i.adouble = 0.5
+    i.afixed = 1.5
+    i.abool = True
+
+    data = pack(fmt, i)
+    print("data:", repr(data))
+    print(unpack(fmt, data))
+    i2 = foo()
+    unpack(fmt, data, i2)
+    print(vars(i2))
+
+
+if __name__ == "__main__":
+    _test()