add iOS

iOS-SwiftUI-Code/GRDB.swift-6.29.3/GRDB/FTS/FTS3.swift

@@ -0,0 +1,190 @@
+/// The virtual table module for the FTS3 full-text engine.
+///
+/// To create FTS3 tables, use the ``Database`` method
+/// ``Database/create(virtualTable:ifNotExists:using:_:)``:
+///
+/// ```swift
+/// // CREATE VIRTUAL TABLE document USING fts3(content)
+/// try db.create(virtualTable: "document", using: FTS3()) { t in
+///     t.column("content")
+/// }
+/// ```
+///
+/// Related SQLite documentation: <https://www.sqlite.org/fts3.html>
+///
+/// ## Topics
+///
+/// ### The FTS3 Module
+///
+/// - ``init()``
+/// - ``FTS3TableDefinition``
+/// - ``FTS3TokenizerDescriptor``
+///
+/// ### Full-Text Search Pattern
+///
+/// - ``FTS3Pattern``
+///
+/// ### Tokenizing Strings
+///
+/// - ``tokenize(_:withTokenizer:)``
+public struct FTS3 {
+    /// Options for Latin script characters.
+    public enum Diacritics: Sendable {
+        /// Do not remove diacritics from Latin script characters. This option
+        /// matches the `remove_diacritics=0` tokenizer argument.
+        ///
+        /// Related SQLite documentation: <https://www.sqlite.org/fts3.html#tokenizer>
+        case keep
+        
+        /// Remove diacritics from Latin script characters. This option matches
+        /// the `remove_diacritics=1` tokenizer argument.
+        case removeLegacy
+        
+        #if GRDBCUSTOMSQLITE
+        /// Remove diacritics from Latin script characters. This option matches
+        /// the `remove_diacritics=2` tokenizer argument.
+        case remove
+        #elseif !GRDBCIPHER
+        /// Remove diacritics from Latin script characters. This option matches
+        /// the `remove_diacritics=2` tokenizer argument.
+        @available(iOS 14, macOS 10.16, tvOS 14, watchOS 7, *) // SQLite 3.27+
+        case remove
+        #endif
+    }
+    
+    /// Creates an FTS3 module.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // CREATE VIRTUAL TABLE document USING fts3(content)
+    /// try db.create(virtualTable: "document", using: FTS3()) { t in
+    ///     t.column("content")
+    /// }
+    /// ```
+    ///
+    /// See ``Database/create(virtualTable:ifNotExists:using:_:)``
+    public init() { }
+    
+    /// Returns an array of tokens found in the string argument.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // ["sqlite", "database"]
+    /// try FTS3.tokenize("SQLite database")
+    ///
+    /// // ["gustave", "doré"])
+    /// try FTS3.tokenize("Gustave Doré")
+    /// ```
+    ///
+    /// Results can be altered with the `tokenizer` argument:
+    ///
+    /// ```swift
+    /// // ["sqlite", "databas"]
+    /// try FTS3.tokenize("SQLite database", withTokenizer: .porter)
+    ///
+    /// // ["gustave", "dore"])
+    /// try FTS3.tokenize("Gustave Doré", withTokenizer: .unicode61())
+    /// ```
+    ///
+    /// Related SQLite documentation:
+    ///
+    /// - <https://www.sqlite.org/fts3.html#tokenizer>
+    /// - <https://www.sqlite.org/fts3.html#querying_tokenizers>
+    ///
+    /// - throws: A ``DatabaseError`` whenever an SQLite error occurs.
+    public static func tokenize(
+        _ string: String,
+        withTokenizer tokenizer: FTS3TokenizerDescriptor = .simple)
+    throws -> [String]
+    {
+        try DatabaseQueue().inDatabase { db in
+            var tokenizerChunks: [String] = []
+            tokenizerChunks.append(tokenizer.name)
+            for option in tokenizer.arguments {
+                tokenizerChunks.append("\"\(option)\"")
+            }
+            let tokenizerSQL = tokenizerChunks.joined(separator: ", ")
+            try db.execute(sql: "CREATE VIRTUAL TABLE tokens USING fts3tokenize(\(tokenizerSQL))")
+            return try String.fetchAll(db, sql: """
+                SELECT token FROM tokens WHERE input = ? ORDER BY position
+                """, arguments: [string])
+        }
+    }
+}
+
+extension FTS3: VirtualTableModule {
+    public var moduleName: String { "fts3" }
+    
+    public func makeTableDefinition(configuration: VirtualTableConfiguration) -> FTS3TableDefinition {
+        FTS3TableDefinition()
+    }
+    
+    public func moduleArguments(for definition: FTS3TableDefinition, in db: Database) -> [String] {
+        var arguments = definition.columns
+        if let tokenizer = definition.tokenizer {
+            if tokenizer.arguments.isEmpty {
+                arguments.append("tokenize=\(tokenizer.name)")
+            } else {
+                arguments.append(
+                    "tokenize=\(tokenizer.name) " + tokenizer.arguments
+                        .map { "\"\($0)\"" as String }
+                        .joined(separator: " "))
+            }
+        }
+        return arguments
+    }
+    
+    public func database(_ db: Database, didCreate tableName: String, using definition: FTS3TableDefinition) { }
+}
+
+/// A `FTS3TableDefinition` lets you define the components of an FTS3
+/// virtual table.
+///
+/// You don't create instances of this class. Instead, you use the `Database`
+/// ``Database/create(virtualTable:ifNotExists:using:_:)`` method:
+///
+/// ```swift
+/// try db.create(virtualTable: "document", using: FTS3()) { t in // t is FTS3TableDefinition
+///     t.column("content")
+/// }
+/// ```
+public final class FTS3TableDefinition {
+    fileprivate var columns: [String] = []
+    
+    /// The virtual table tokenizer.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // CREATE VIRTUAL TABLE documents USING fts3(tokenize=porter)
+    /// try db.create(virtualTable: "document", using: FTS3()) { t in
+    ///     t.tokenizer = .porter
+    /// }
+    /// ```
+    ///
+    /// Related SQLite documentation: <https://www.sqlite.org/fts3.html#creating_and_destroying_fts_tables>
+    public var tokenizer: FTS3TokenizerDescriptor?
+    
+    /// Appends a table column.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // CREATE VIRTUAL TABLE document USING fts3(content)
+    /// try db.create(virtualTable: "document", using: FTS3()) { t in
+    ///     t.column("content")
+    /// }
+    /// ```
+    ///
+    /// - parameter name: the column name.
+    public func column(_ name: String) {
+        columns.append(name)
+    }
+}
+
+// Explicit non-conformance to Sendable: `FTS3TableDefinition` is a mutable
+// class and there is no known reason for making it thread-safe.
+@available(*, unavailable)
+extension FTS3TableDefinition: Sendable { }