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Add BaseEncoding.ignoreCase().
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Calling `baseEncoding.ignoreCase()` returns a new `BaseEncoding` instance equivalent to `baseEncoding` except that it accepts either case when decoding. When *en*coding it continues to use whatever case the original `baseEncoding` used.

RELNOTES=`BaseEncoding` acquires a new `ignoreCase()` method to support case-insensitive decoding.
PiperOrigin-RevId: 469812601
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@eamonnmcmanus
eamonnmcmanus authored and Google Java Core Libraries committed Aug 24, 2022
1 parent 0f1d935 commit 9c1e5de
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Showing 4 changed files with 236 additions and 20 deletions.
51 changes: 49 additions & 2 deletions android/guava-tests/test/com/google/common/io/BaseEncodingTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -125,7 +125,6 @@ public void testBase64CannotUpperCase() {
base64().upperCase();
fail();
} catch (IllegalStateException expected) {
// success
}
}

Expand All @@ -134,7 +133,14 @@ public void testBase64CannotLowerCase() {
base64().lowerCase();
fail();
} catch (IllegalStateException expected) {
// success
}
}

public void testBase64CannotIgnoreCase() {
try {
base64().ignoreCase();
fail();
} catch (IllegalStateException expected) {
}
}

Expand Down Expand Up @@ -265,6 +271,18 @@ public void testBase32UpperCaseIsNoOp() {
assertThat(base32().upperCase()).isSameInstanceAs(base32());
}

public void testBase32LowerCase() {
testEncodingWithCasing(base32().lowerCase(), "foobar", "mzxw6ytboi======");
}

public void testBase32IgnoreCase() {
BaseEncoding ignoreCase = base32().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base32());
assertThat(ignoreCase).isSameInstanceAs(base32().ignoreCase());
testDecodes(ignoreCase, "MZXW6YTBOI======", "foobar");
testDecodes(ignoreCase, "mzxw6ytboi======", "foobar");
}

public void testBase32Offset() {
testEncodesWithOffset(base32(), "foobar", 0, 6, "MZXW6YTBOI======");
testEncodesWithOffset(base32(), "foobar", 1, 5, "N5XWEYLS");
Expand Down Expand Up @@ -335,6 +353,33 @@ public void testBase16UpperCaseIsNoOp() {
assertThat(base16().upperCase()).isSameInstanceAs(base16());
}

public void testBase16LowerCase() {
BaseEncoding lowerCase = base16().lowerCase();
assertThat(lowerCase).isNotSameInstanceAs(base16());
assertThat(lowerCase).isSameInstanceAs(base16().lowerCase());
testEncodingWithCasing(lowerCase, "foobar", "666f6f626172");
}

public void testBase16IgnoreCase() {
BaseEncoding ignoreCase = base16().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base16());
assertThat(ignoreCase).isSameInstanceAs(base16().ignoreCase());
testEncodingWithCasing(ignoreCase, "foobar", "666F6F626172");
testDecodes(ignoreCase, "666F6F626172", "foobar");
testDecodes(ignoreCase, "666f6f626172", "foobar");
testDecodes(ignoreCase, "666F6f626172", "foobar");
}

public void testBase16LowerCaseIgnoreCase() {
BaseEncoding ignoreCase = base16().lowerCase().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base16());
assertThat(ignoreCase).isSameInstanceAs(base16().lowerCase().ignoreCase());
testEncodingWithCasing(ignoreCase, "foobar", "666f6f626172");
testDecodes(ignoreCase, "666F6F626172", "foobar");
testDecodes(ignoreCase, "666f6f626172", "foobar");
testDecodes(ignoreCase, "666F6f626172", "foobar");
}

public void testBase16InvalidDecodings() {
// These contain bytes not in the decodabet.
assertFailsToDecode(base16(), "\n\n", "Unrecognized character: 0xa");
Expand All @@ -344,6 +389,8 @@ public void testBase16InvalidDecodings() {
assertFailsToDecode(base16(), "ABC");
// These have a combination of invalid length and unrecognized characters.
assertFailsToDecode(base16(), "?", "Invalid input length 1");
assertFailsToDecode(base16(), "ab");
assertFailsToDecode(base16().lowerCase(), "AB");
}

public void testBase16Offset() {
Expand Down
77 changes: 69 additions & 8 deletions android/guava/src/com/google/common/io/BaseEncoding.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -318,6 +318,15 @@ CharSequence trimTrailingPadding(CharSequence chars) {
*/
public abstract BaseEncoding lowerCase();

/**
* Returns an encoding that behaves equivalently to this encoding, but decodes letters without
* regard to case.
*
* @throws IllegalStateException if the alphabet used by this encoding contains mixed upper- and
* lower-case characters
*/
public abstract BaseEncoding ignoreCase();

private static final BaseEncoding BASE64 =
new Base64Encoding(
"base64()", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", '=');
Expand Down Expand Up @@ -428,8 +437,13 @@ private static final class Alphabet {
final int bytesPerChunk;
private final byte[] decodabet;
private final boolean[] validPadding;
private final boolean ignoreCase;

Alphabet(String name, char[] chars) {
this(name, chars, decodabetFor(chars), /* ignoreCase= */ false);
}

private Alphabet(String name, char[] chars, byte[] decodabet, boolean ignoreCase) {
this.name = checkNotNull(name);
this.chars = checkNotNull(chars);
try {
Expand All @@ -452,6 +466,17 @@ private static final class Alphabet {

this.mask = chars.length - 1;

this.decodabet = decodabet;

boolean[] validPadding = new boolean[charsPerChunk];
for (int i = 0; i < bytesPerChunk; i++) {
validPadding[divide(i * 8, bitsPerChar, CEILING)] = true;
}
this.validPadding = validPadding;
this.ignoreCase = ignoreCase;
}

private static byte[] decodabetFor(char[] chars) {
byte[] decodabet = new byte[Ascii.MAX + 1];
Arrays.fill(decodabet, (byte) -1);
for (int i = 0; i < chars.length; i++) {
Expand All @@ -460,13 +485,33 @@ private static final class Alphabet {
checkArgument(decodabet[c] == -1, "Duplicate character: %s", c);
decodabet[c] = (byte) i;
}
this.decodabet = decodabet;
return decodabet;
}

boolean[] validPadding = new boolean[charsPerChunk];
for (int i = 0; i < bytesPerChunk; i++) {
validPadding[divide(i * 8, bitsPerChar, CEILING)] = true;
/** Returns an equivalent {@code Alphabet} except it ignores case. */
Alphabet ignoreCase() {
if (ignoreCase) {
return this;
}
this.validPadding = validPadding;

// We can't use .clone() because of GWT.
byte[] newDecodabet = Arrays.copyOf(decodabet, decodabet.length);
for (int upper = 'A'; upper <= 'Z'; upper++) {
int lower = upper | 0x20;
byte decodeUpper = decodabet[upper];
byte decodeLower = decodabet[lower];
if (decodeUpper == -1) {
newDecodabet[upper] = decodeLower;
} else {
checkState(
decodeLower == -1,
"Can't ignoreCase() since '%s' and '%s' encode different values",
(char) upper,
(char) lower);
newDecodabet[lower] = decodeUpper;
}
}
return new Alphabet(name + ".ignoreCase()", chars, newDecodabet, /* ignoreCase= */ true);
}

char encode(int bits) {
Expand Down Expand Up @@ -551,14 +596,14 @@ public String toString() {
public boolean equals(@CheckForNull Object other) {
if (other instanceof Alphabet) {
Alphabet that = (Alphabet) other;
return Arrays.equals(this.chars, that.chars);
return this.ignoreCase == that.ignoreCase && Arrays.equals(this.chars, that.chars);
}
return false;
}

@Override
public int hashCode() {
return Arrays.hashCode(chars);
return Arrays.hashCode(chars) + (ignoreCase ? 1231 : 1237);
}
}

Expand Down Expand Up @@ -832,6 +877,7 @@ public BaseEncoding withSeparator(String separator, int afterEveryChars) {

@LazyInit @CheckForNull private transient BaseEncoding upperCase;
@LazyInit @CheckForNull private transient BaseEncoding lowerCase;
@LazyInit @CheckForNull private transient BaseEncoding ignoreCase;

@Override
public BaseEncoding upperCase() {
Expand All @@ -853,14 +899,24 @@ public BaseEncoding lowerCase() {
return result;
}

@Override
public BaseEncoding ignoreCase() {
BaseEncoding result = ignoreCase;
if (result == null) {
Alphabet ignore = alphabet.ignoreCase();
result = ignoreCase = (ignore == alphabet) ? this : newInstance(ignore, paddingChar);
}
return result;
}

BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
return new StandardBaseEncoding(alphabet, paddingChar);
}

@Override
public String toString() {
StringBuilder builder = new StringBuilder("BaseEncoding.");
builder.append(alphabet.toString());
builder.append(alphabet);
if (8 % alphabet.bitsPerChar != 0) {
if (paddingChar == null) {
builder.append(".omitPadding()");
Expand Down Expand Up @@ -1170,6 +1226,11 @@ public BaseEncoding lowerCase() {
return delegate.lowerCase().withSeparator(separator, afterEveryChars);
}

@Override
public BaseEncoding ignoreCase() {
return delegate.ignoreCase().withSeparator(separator, afterEveryChars);
}

@Override
public String toString() {
return delegate + ".withSeparator(\"" + separator + "\", " + afterEveryChars + ")";
Expand Down
51 changes: 49 additions & 2 deletions guava-tests/test/com/google/common/io/BaseEncodingTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -125,7 +125,6 @@ public void testBase64CannotUpperCase() {
base64().upperCase();
fail();
} catch (IllegalStateException expected) {
// success
}
}

Expand All @@ -134,7 +133,14 @@ public void testBase64CannotLowerCase() {
base64().lowerCase();
fail();
} catch (IllegalStateException expected) {
// success
}
}

public void testBase64CannotIgnoreCase() {
try {
base64().ignoreCase();
fail();
} catch (IllegalStateException expected) {
}
}

Expand Down Expand Up @@ -265,6 +271,18 @@ public void testBase32UpperCaseIsNoOp() {
assertThat(base32().upperCase()).isSameInstanceAs(base32());
}

public void testBase32LowerCase() {
testEncodingWithCasing(base32().lowerCase(), "foobar", "mzxw6ytboi======");
}

public void testBase32IgnoreCase() {
BaseEncoding ignoreCase = base32().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base32());
assertThat(ignoreCase).isSameInstanceAs(base32().ignoreCase());
testDecodes(ignoreCase, "MZXW6YTBOI======", "foobar");
testDecodes(ignoreCase, "mzxw6ytboi======", "foobar");
}

public void testBase32Offset() {
testEncodesWithOffset(base32(), "foobar", 0, 6, "MZXW6YTBOI======");
testEncodesWithOffset(base32(), "foobar", 1, 5, "N5XWEYLS");
Expand Down Expand Up @@ -335,6 +353,33 @@ public void testBase16UpperCaseIsNoOp() {
assertThat(base16().upperCase()).isSameInstanceAs(base16());
}

public void testBase16LowerCase() {
BaseEncoding lowerCase = base16().lowerCase();
assertThat(lowerCase).isNotSameInstanceAs(base16());
assertThat(lowerCase).isSameInstanceAs(base16().lowerCase());
testEncodingWithCasing(lowerCase, "foobar", "666f6f626172");
}

public void testBase16IgnoreCase() {
BaseEncoding ignoreCase = base16().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base16());
assertThat(ignoreCase).isSameInstanceAs(base16().ignoreCase());
testEncodingWithCasing(ignoreCase, "foobar", "666F6F626172");
testDecodes(ignoreCase, "666F6F626172", "foobar");
testDecodes(ignoreCase, "666f6f626172", "foobar");
testDecodes(ignoreCase, "666F6f626172", "foobar");
}

public void testBase16LowerCaseIgnoreCase() {
BaseEncoding ignoreCase = base16().lowerCase().ignoreCase();
assertThat(ignoreCase).isNotSameInstanceAs(base16());
assertThat(ignoreCase).isSameInstanceAs(base16().lowerCase().ignoreCase());
testEncodingWithCasing(ignoreCase, "foobar", "666f6f626172");
testDecodes(ignoreCase, "666F6F626172", "foobar");
testDecodes(ignoreCase, "666f6f626172", "foobar");
testDecodes(ignoreCase, "666F6f626172", "foobar");
}

public void testBase16InvalidDecodings() {
// These contain bytes not in the decodabet.
assertFailsToDecode(base16(), "\n\n", "Unrecognized character: 0xa");
Expand All @@ -344,6 +389,8 @@ public void testBase16InvalidDecodings() {
assertFailsToDecode(base16(), "ABC");
// These have a combination of invalid length and unrecognized characters.
assertFailsToDecode(base16(), "?", "Invalid input length 1");
assertFailsToDecode(base16(), "ab");
assertFailsToDecode(base16().lowerCase(), "AB");
}

public void testBase16Offset() {
Expand Down
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