Add snippet to subset fpgm functions

Snippets/fontTools

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+../Lib/fontTools

Snippets/subset-fpgm.py

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+
+import sys
+from fontTools.ttLib import TTFont
+
+if len(sys.argv) < 2:
+	print "usage: subset-fpgm.py fontfile.ttf func-number..."
+	sys.exit(1)
+fontfile = sys.argv[1]
+func_nums = [int(x) for x in sys.argv[2:]]
+
+font = TTFont(fontfile)
+fpgm = font['fpgm']
+
+# Parse fpgm
+asm = fpgm.program.getAssembly()
+funcs = {}
+stack = []
+tokens = iter(asm)
+for token in tokens:
+	if token.startswith("PUSH") or token.startswith("NPUSH"):
+		for token in tokens:
+			try:
+				num = int(token)
+				stack.append(num)
+			except ValueError:
+				break
+	if token.startswith("FDEF"):
+		num = stack.pop()
+		body = []
+		for token in tokens:
+			if token.startswith("ENDF"):
+				break
+			body.append(token)
+		funcs[num] = body
+		continue
+	assert 0, "Unexpected token in fpgm: %s" % token
+
+# Subset!
+funcs = {i:funcs[i] for i in func_nums}
+
+# Put it back together:
+asm = []
+if funcs:
+	asm.append("PUSH[ ]")
+nums = sorted(funcs.keys())
+asm.extend(str(i) for i in nums)
+for i in nums:
+	asm.append("FDEF[ ]")
+	asm.extend(funcs[i])
+	asm.append("ENDF[ ]")
+
+import pprint
+pprint.pprint(asm)
+
+fpgm.program.fromAssembly(asm)
+# Make sure it compiles
+fpgm.program.getBytecode()