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-rw-r--r--storage/mozStorageSQLFunctions.cpp365
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diff --git a/storage/mozStorageSQLFunctions.cpp b/storage/mozStorageSQLFunctions.cpp
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "mozStorageSQLFunctions.h"
+#include "nsTArray.h"
+#include "nsUnicharUtils.h"
+#include <algorithm>
+
+namespace mozilla {
+namespace storage {
+
+////////////////////////////////////////////////////////////////////////////////
+//// Local Helper Functions
+
+namespace {
+
+/**
+ * Performs the LIKE comparison of a string against a pattern. For more detail
+ * see http://www.sqlite.org/lang_expr.html#like.
+ *
+ * @param aPatternItr
+ * An iterator at the start of the pattern to check for.
+ * @param aPatternEnd
+ * An iterator at the end of the pattern to check for.
+ * @param aStringItr
+ * An iterator at the start of the string to check for the pattern.
+ * @param aStringEnd
+ * An iterator at the end of the string to check for the pattern.
+ * @param aEscapeChar
+ * The character to use for escaping symbols in the pattern.
+ * @return 1 if the pattern is found, 0 otherwise.
+ */
+int likeCompare(nsAString::const_iterator aPatternItr,
+ nsAString::const_iterator aPatternEnd,
+ nsAString::const_iterator aStringItr,
+ nsAString::const_iterator aStringEnd, char16_t aEscapeChar) {
+ const char16_t MATCH_ALL('%');
+ const char16_t MATCH_ONE('_');
+
+ bool lastWasEscape = false;
+ while (aPatternItr != aPatternEnd) {
+ /**
+ * What we do in here is take a look at each character from the input
+ * pattern, and do something with it. There are 4 possibilities:
+ * 1) character is an un-escaped match-all character
+ * 2) character is an un-escaped match-one character
+ * 3) character is an un-escaped escape character
+ * 4) character is not any of the above
+ */
+ if (!lastWasEscape && *aPatternItr == MATCH_ALL) {
+ // CASE 1
+ /**
+ * Now we need to skip any MATCH_ALL or MATCH_ONE characters that follow a
+ * MATCH_ALL character. For each MATCH_ONE character, skip one character
+ * in the pattern string.
+ */
+ while (*aPatternItr == MATCH_ALL || *aPatternItr == MATCH_ONE) {
+ if (*aPatternItr == MATCH_ONE) {
+ // If we've hit the end of the string we are testing, no match
+ if (aStringItr == aStringEnd) return 0;
+ aStringItr++;
+ }
+ aPatternItr++;
+ }
+
+ // If we've hit the end of the pattern string, match
+ if (aPatternItr == aPatternEnd) return 1;
+
+ while (aStringItr != aStringEnd) {
+ if (likeCompare(aPatternItr, aPatternEnd, aStringItr, aStringEnd,
+ aEscapeChar)) {
+ // we've hit a match, so indicate this
+ return 1;
+ }
+ aStringItr++;
+ }
+
+ // No match
+ return 0;
+ } else if (!lastWasEscape && *aPatternItr == MATCH_ONE) {
+ // CASE 2
+ if (aStringItr == aStringEnd) {
+ // If we've hit the end of the string we are testing, no match
+ return 0;
+ }
+ aStringItr++;
+ lastWasEscape = false;
+ } else if (!lastWasEscape && *aPatternItr == aEscapeChar) {
+ // CASE 3
+ lastWasEscape = true;
+ } else {
+ // CASE 4
+ if (::ToUpperCase(*aStringItr) != ::ToUpperCase(*aPatternItr)) {
+ // If we've hit a point where the strings don't match, there is no match
+ return 0;
+ }
+ aStringItr++;
+ lastWasEscape = false;
+ }
+
+ aPatternItr++;
+ }
+
+ return aStringItr == aStringEnd;
+}
+
+/**
+ * Compute the Levenshtein Edit Distance between two strings.
+ *
+ * @param aStringS
+ * a string
+ * @param aStringT
+ * another string
+ * @param _result
+ * an outparam that will receive the edit distance between the arguments
+ * @return a Sqlite result code, e.g. SQLITE_OK, SQLITE_NOMEM, etc.
+ */
+int levenshteinDistance(const nsAString& aStringS, const nsAString& aStringT,
+ int* _result) {
+ // Set the result to a non-sensical value in case we encounter an error.
+ *_result = -1;
+
+ const uint32_t sLen = aStringS.Length();
+ const uint32_t tLen = aStringT.Length();
+
+ if (sLen == 0) {
+ *_result = tLen;
+ return SQLITE_OK;
+ }
+ if (tLen == 0) {
+ *_result = sLen;
+ return SQLITE_OK;
+ }
+
+ // Notionally, Levenshtein Distance is computed in a matrix. If we
+ // assume s = "span" and t = "spam", the matrix would look like this:
+ // s -->
+ // t s p a n
+ // | 0 1 2 3 4
+ // V s 1 * * * *
+ // p 2 * * * *
+ // a 3 * * * *
+ // m 4 * * * *
+ //
+ // Note that the row width is sLen + 1 and the column height is tLen + 1,
+ // where sLen is the length of the string "s" and tLen is the length of "t".
+ // The first row and the first column are initialized as shown, and
+ // the algorithm computes the remaining cells row-by-row, and
+ // left-to-right within each row. The computation only requires that
+ // we be able to see the current row and the previous one.
+
+ // Allocate memory for two rows.
+ AutoTArray<int, nsAutoString::kStorageSize> row1;
+ AutoTArray<int, nsAutoString::kStorageSize> row2;
+
+ // Declare the raw pointers that will actually be used to access the memory.
+ int* prevRow = row1.AppendElements(sLen + 1);
+ int* currRow = row2.AppendElements(sLen + 1);
+
+ // Initialize the first row.
+ for (uint32_t i = 0; i <= sLen; i++) prevRow[i] = i;
+
+ const char16_t* s = aStringS.BeginReading();
+ const char16_t* t = aStringT.BeginReading();
+
+ // Compute the empty cells in the "matrix" row-by-row, starting with
+ // the second row.
+ for (uint32_t ti = 1; ti <= tLen; ti++) {
+ // Initialize the first cell in this row.
+ currRow[0] = ti;
+
+ // Get the character from "t" that corresponds to this row.
+ const char16_t tch = t[ti - 1];
+
+ // Compute the remaining cells in this row, left-to-right,
+ // starting at the second column (and first character of "s").
+ for (uint32_t si = 1; si <= sLen; si++) {
+ // Get the character from "s" that corresponds to this column,
+ // compare it to the t-character, and compute the "cost".
+ const char16_t sch = s[si - 1];
+ int cost = (sch == tch) ? 0 : 1;
+
+ // ............ We want to calculate the value of cell "d" from
+ // ...ab....... the previously calculated (or initialized) cells
+ // ...cd....... "a", "b", and "c", where d = min(a', b', c').
+ // ............
+ int aPrime = prevRow[si - 1] + cost;
+ int bPrime = prevRow[si] + 1;
+ int cPrime = currRow[si - 1] + 1;
+ currRow[si] = std::min(aPrime, std::min(bPrime, cPrime));
+ }
+
+ // Advance to the next row. The current row becomes the previous
+ // row and we recycle the old previous row as the new current row.
+ // We don't need to re-initialize the new current row since we will
+ // rewrite all of its cells anyway.
+ int* oldPrevRow = prevRow;
+ prevRow = currRow;
+ currRow = oldPrevRow;
+ }
+
+ // The final result is the value of the last cell in the last row.
+ // Note that that's now in the "previous" row, since we just swapped them.
+ *_result = prevRow[sLen];
+ return SQLITE_OK;
+}
+
+// This struct is used only by registerFunctions below, but ISO C++98 forbids
+// instantiating a template dependent on a locally-defined type. Boo-urns!
+struct Functions {
+ const char* zName;
+ int nArg;
+ int enc;
+ void* pContext;
+ void (*xFunc)(::sqlite3_context*, int, sqlite3_value**);
+};
+
+} // namespace
+
+////////////////////////////////////////////////////////////////////////////////
+//// Exposed Functions
+
+int registerFunctions(sqlite3* aDB) {
+ Functions functions[] = {
+ {"lower", 1, SQLITE_UTF16, 0, caseFunction},
+ {"lower", 1, SQLITE_UTF8, 0, caseFunction},
+ {"upper", 1, SQLITE_UTF16, (void*)1, caseFunction},
+ {"upper", 1, SQLITE_UTF8, (void*)1, caseFunction},
+
+ {"like", 2, SQLITE_UTF16, 0, likeFunction},
+ {"like", 2, SQLITE_UTF8, 0, likeFunction},
+ {"like", 3, SQLITE_UTF16, 0, likeFunction},
+ {"like", 3, SQLITE_UTF8, 0, likeFunction},
+
+ {"levenshteinDistance", 2, SQLITE_UTF16, 0, levenshteinDistanceFunction},
+ {"levenshteinDistance", 2, SQLITE_UTF8, 0, levenshteinDistanceFunction},
+
+ {"utf16Length", 1, SQLITE_UTF16, 0, utf16LengthFunction},
+ {"utf16Length", 1, SQLITE_UTF8, 0, utf16LengthFunction},
+ };
+
+ int rv = SQLITE_OK;
+ for (size_t i = 0; SQLITE_OK == rv && i < ArrayLength(functions); ++i) {
+ struct Functions* p = &functions[i];
+ rv = ::sqlite3_create_function(aDB, p->zName, p->nArg, p->enc, p->pContext,
+ p->xFunc, nullptr, nullptr);
+ }
+
+ return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//// SQL Functions
+
+void caseFunction(sqlite3_context* aCtx, int aArgc, sqlite3_value** aArgv) {
+ NS_ASSERTION(1 == aArgc, "Invalid number of arguments!");
+
+ const char16_t* value =
+ static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[0]));
+ nsAutoString data(value,
+ ::sqlite3_value_bytes16(aArgv[0]) / sizeof(char16_t));
+ bool toUpper = ::sqlite3_user_data(aCtx) ? true : false;
+
+ if (toUpper)
+ ::ToUpperCase(data);
+ else
+ ::ToLowerCase(data);
+
+ // Set the result.
+ ::sqlite3_result_text16(aCtx, data.get(), data.Length() * sizeof(char16_t),
+ SQLITE_TRANSIENT);
+}
+
+/**
+ * This implements the like() SQL function. This is used by the LIKE operator.
+ * The SQL statement 'A LIKE B' is implemented as 'like(B, A)', and if there is
+ * an escape character, say E, it is implemented as 'like(B, A, E)'.
+ */
+void likeFunction(sqlite3_context* aCtx, int aArgc, sqlite3_value** aArgv) {
+ NS_ASSERTION(2 == aArgc || 3 == aArgc, "Invalid number of arguments!");
+
+ if (::sqlite3_value_bytes(aArgv[0]) > SQLITE_MAX_LIKE_PATTERN_LENGTH) {
+ ::sqlite3_result_error(aCtx, "LIKE or GLOB pattern too complex",
+ SQLITE_TOOBIG);
+ return;
+ }
+
+ if (!::sqlite3_value_text16(aArgv[0]) || !::sqlite3_value_text16(aArgv[1]))
+ return;
+
+ const char16_t* a =
+ static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[1]));
+ int aLen = ::sqlite3_value_bytes16(aArgv[1]) / sizeof(char16_t);
+ nsDependentString A(a, aLen);
+
+ const char16_t* b =
+ static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[0]));
+ int bLen = ::sqlite3_value_bytes16(aArgv[0]) / sizeof(char16_t);
+ nsDependentString B(b, bLen);
+ NS_ASSERTION(!B.IsEmpty(), "LIKE string must not be null!");
+
+ char16_t E = 0;
+ if (3 == aArgc)
+ E = static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[2]))[0];
+
+ nsAString::const_iterator itrString, endString;
+ A.BeginReading(itrString);
+ A.EndReading(endString);
+ nsAString::const_iterator itrPattern, endPattern;
+ B.BeginReading(itrPattern);
+ B.EndReading(endPattern);
+ ::sqlite3_result_int(
+ aCtx, likeCompare(itrPattern, endPattern, itrString, endString, E));
+}
+
+void levenshteinDistanceFunction(sqlite3_context* aCtx, int aArgc,
+ sqlite3_value** aArgv) {
+ NS_ASSERTION(2 == aArgc, "Invalid number of arguments!");
+
+ // If either argument is a SQL NULL, then return SQL NULL.
+ if (::sqlite3_value_type(aArgv[0]) == SQLITE_NULL ||
+ ::sqlite3_value_type(aArgv[1]) == SQLITE_NULL) {
+ ::sqlite3_result_null(aCtx);
+ return;
+ }
+
+ const char16_t* a =
+ static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[0]));
+ int aLen = ::sqlite3_value_bytes16(aArgv[0]) / sizeof(char16_t);
+
+ const char16_t* b =
+ static_cast<const char16_t*>(::sqlite3_value_text16(aArgv[1]));
+ int bLen = ::sqlite3_value_bytes16(aArgv[1]) / sizeof(char16_t);
+
+ // Compute the Levenshtein Distance, and return the result (or error).
+ int distance = -1;
+ const nsDependentString A(a, aLen);
+ const nsDependentString B(b, bLen);
+ int status = levenshteinDistance(A, B, &distance);
+ if (status == SQLITE_OK) {
+ ::sqlite3_result_int(aCtx, distance);
+ } else if (status == SQLITE_NOMEM) {
+ ::sqlite3_result_error_nomem(aCtx);
+ } else {
+ ::sqlite3_result_error(aCtx, "User function returned error code", -1);
+ }
+}
+
+void utf16LengthFunction(sqlite3_context* aCtx, int aArgc,
+ sqlite3_value** aArgv) {
+ NS_ASSERTION(1 == aArgc, "Invalid number of arguments!");
+
+ int len = ::sqlite3_value_bytes16(aArgv[0]) / sizeof(char16_t);
+
+ // Set the result.
+ ::sqlite3_result_int(aCtx, len);
+}
+
+} // namespace storage
+} // namespace mozilla
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