tiny.sql.StatementCursor

1pub const Cursor = struct {2    allocator: Allocator,3    relation: *plan.PreparedRelation,4    reader: ?plan.RelationRead,5    fields: []const execute_mod.ProjectedColumn,6    access: access_mod.SelectAccess,7    predicates: []const ast_mod.Predicate,8    predicate_values: []row.Value,9    state: CursorState,10    window: execute_mod.Window = .{},11    row_buffer: std.ArrayList(u8) = .empty,12    table_row: ?[]u8 = null,1314    pub fn deinit(self: *Cursor) void {15        self.releaseTableRow();16        switch (self.state) {17            .empty => {},18            .single => |single| if (single.bytes) |bytes| self.allocator.free(bytes),19            .rowid => |*scan| scan.deinit(),20            .index => |*index_cursor| index_cursor.scan.deinit(),21            .scan => |*scan| scan.deinit(),22            .sorted => |sorted| {23                result_mod.freeSelectedRows(self.allocator, sorted.rows);24                self.allocator.free(sorted.rows);25            },26        }27        if (self.reader) |*reader| reader.deinit();28        self.row_buffer.deinit(self.allocator);29        for (self.predicate_values) |value| result_mod.freeValue(self.allocator, value);30        self.allocator.free(self.predicate_values);31        self.allocator.free(self.predicates);32        self.* = undefined;33    }3435    pub fn next(self: *Cursor) ast_mod.Error!?[]const u8 {36        const phase = trace.scope("statement.cursor.next");37        defer phase.end();3839        self.releaseTableRow();40        if (self.window.full()) return null;41        return switch (self.state) {42            .empty => null,43            .single => |*single| self.nextSingle(single),44            .rowid => |*scan| self.nextRowid(scan),45            .index => |*index_cursor| self.nextIndex(index_cursor),46            .scan => |*scan| self.nextScan(scan),47            .sorted => |*sorted| self.nextSorted(sorted),48        };49    }5051    pub fn nextSingle(self: *Cursor, single: *SingleCursor) ast_mod.Error!?[]const u8 {52        if (single.emitted) return null;53        single.emitted = true;54        if (!self.window.admit()) return null;55        return single.bytes;56    }5758    pub fn nextSorted(self: *Cursor, sorted: *SortedCursor) ast_mod.Error!?[]const u8 {59        _ = self;60        if (sorted.index >= sorted.rows.len) return null;61        const bytes = sorted.rows[sorted.index];62        sorted.index += 1;63        return bytes;64    }6566    pub fn nextRowid(self: *Cursor, scan: *relation_mod.Scan) ast_mod.Error!?[]const u8 {67        const access = switch (self.access) {68            .rowid => |rowid_access| rowid_access,69            else => unreachable,70        };71        const rowid = try predicate_mod.rowidFromValue(self.predicate_values[access.predicate_index]);72        while (try scan.next()) |entry| {73            if (!predicate_mod.rowidMatches(entry.rowid, access.operator, rowid)) continue;74            if (!try predicate_mod.rowBytesMatchPredicates(self.predicates, self.predicate_values, &self.relation.handle, entry.rowid, entry.bytes)) continue;75            if (!self.window.admit()) continue;76            return try self.tableEntry(entry.rowid, entry.bytes);77        }78        return null;79    }8081    pub fn nextIndex(self: *Cursor, index_cursor: *IndexCursor) ast_mod.Error!?[]const u8 {82        const index_slot = switch (self.access) {83            .index => |index_access| index_access.index_slot,84            else => unreachable,85        };86        while (try index_cursor.scan.next()) |entry| {87            if (index_cursor.covered) {88                var index_values: [catalog_mod.max_columns]row.Value = undefined;89                var index_scratch: [page.size]u8 = undefined;90                const values = try predicate_mod.coveredIndexValues(91                    self.predicates,92                    self.predicate_values,93                    &self.relation.handle,94                    index_slot,95                    entry,96                    &index_values,97                    &index_scratch,98                ) orelse continue;99                if (!self.window.admit()) continue;100                return try result_mod.selectedIndexRowInto(101                    self.allocator,102                    &self.row_buffer,103                    self.fields,104                    &self.relation.handle,105                    index_slot,106                    values,107                    entry.rowid,108                );109            }110            const reader = if (self.reader) |*value| value else unreachable;111            const bytes = (try reader.get(self.allocator, entry.rowid)) orelse continue;112            self.table_row = bytes;113            if (!try predicate_mod.rowBytesMatchPredicates(self.predicates, self.predicate_values, &self.relation.handle, entry.rowid, bytes)) {114                self.releaseTableRow();115                continue;116            }117            if (!self.window.admit()) {118                self.releaseTableRow();119                continue;120            }121            if (self.fields.len == 0) return bytes;122            const projected = try result_mod.selectedRowInto(self.allocator, &self.row_buffer, self.fields, entry.rowid, bytes);123            self.releaseTableRow();124            return projected;125        }126        return null;127    }128129    pub fn nextScan(self: *Cursor, scan: *relation_mod.Scan) ast_mod.Error!?[]const u8 {130        while (try scan.next()) |entry| {131            if (!try predicate_mod.rowBytesMatchPredicates(self.predicates, self.predicate_values, &self.relation.handle, entry.rowid, entry.bytes)) continue;132            if (!self.window.admit()) continue;133            return try self.tableEntry(entry.rowid, entry.bytes);134        }135        return null;136    }137138    pub fn tableEntry(self: *Cursor, rowid: i64, bytes: []const u8) ast_mod.Error![]const u8 {139        if (self.fields.len == 0) return bytes;140        return try result_mod.selectedRowInto(self.allocator, &self.row_buffer, self.fields, rowid, bytes);141    }142143    pub fn releaseTableRow(self: *Cursor) void {144        if (self.table_row) |bytes| {145            self.allocator.free(bytes);146            self.table_row = null;147        }148    }149};

1pub const StatementCursor = statement.Cursor;