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80 lines
2.1 KiB
Python
80 lines
2.1 KiB
Python
# Step 04 - generate Java literals.
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#
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# Java byte-code has ridiculous restrictions. There is no such thing as
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# "array literal" - those are implemented as series of data[x] = y;
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# as a consequence N-byte array will use 7N bytes in class, plus N bytes
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# in instantiated variable. Also no literal could be longer than 64KiB.
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#
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# To keep dictionary data compact both in source code and in compiled format
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# we use the following tricks:
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# * use String as a data container
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# * store only lowest 7 bits; i.e. all characters fit ASCII table; this allows
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# efficient conversion to byte array; also ASCII characters use only 1 byte
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#. of memory (UTF-8 encoding)
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# * RLE-compress sequence of 8-th bits
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#
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# This script generates literals used in Java code.
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bin_path = "dictionary.bin"
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with open(bin_path, "rb") as raw:
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data = raw.read()
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low = []
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hi = []
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is_skip = True
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skip_flip_offset = 36
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cntr = skip_flip_offset
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for b in data:
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value = ord(b)
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low.append(chr(value & 0x7F))
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if is_skip:
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if value < 0x80:
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cntr += 1
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else:
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is_skip = False
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hi.append(unichr(cntr))
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cntr = skip_flip_offset + 1
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else:
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if value >= 0x80:
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cntr += 1
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else:
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is_skip = True
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hi.append(unichr(cntr))
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cntr = skip_flip_offset + 1
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hi.append(unichr(cntr))
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low0 = low[0 : len(low) // 2]
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low1 = low[len(low) // 2 : len(low)]
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def escape(chars):
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result = []
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for c in chars:
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if "\r" == c:
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result.append("\\r")
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elif "\n" == c:
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result.append("\\n")
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elif "\t" == c:
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result.append("\\t")
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elif "\"" == c:
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result.append("\\\"")
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elif "\\" == c:
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result.append("\\\\")
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elif ord(c) < 32 or ord(c) >= 127:
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result.append("\\u%04X" % ord(c))
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else:
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result.append(c);
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return result
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source_code = [
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" private static final String DATA0 = \"", "".join(escape(low0)), "\";\n",
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" private static final String DATA1 = \"", "".join(escape(low1)), "\";\n",
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" private static final String SKIP_FLIP = \"", "".join(escape(hi)), "\";\n"
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]
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src_path = "DictionaryData.inc.java"
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with open(src_path, "w") as source:
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source.write("".join(source_code))
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