diff --git a/src/expr.zig b/src/expr.zig index 8593d67..059d221 100644 --- a/src/expr.zig +++ b/src/expr.zig @@ -155,3 +155,163 @@ const Parser = struct { const value = try rawValue.dupe(self.allocator); self.advance(); + const cond = Condition{ .field = fieldCopy, .value = value }; + if (std.mem.eql(u8, op, "eq")) return .{ .eq = cond }; + if (std.mem.eql(u8, op, "ne")) return .{ .ne = cond }; + if (std.mem.eql(u8, op, "lt")) return .{ .lt = cond }; + if (std.mem.eql(u8, op, "lte")) return .{ .lte = cond }; + if (std.mem.eql(u8, op, "gt")) return .{ .gt = cond }; + if (std.mem.eql(u8, op, "gte")) return .{ .gte = cond }; + if (std.mem.eql(u8, op, "like")) { + if (value != .text) return error.InvalidValue; + return .{ .like = cond }; + } + return error.UnknownOperator; + } + + /// `field in (v1 v2 ...)`: desugars to an `or_` of per-value `eq` + /// leaves against the same field, sharing the one field-name copy the + /// caller already made (Condition never owns `field`, so aliasing it + /// across every leaf is safe). A single value collapses to a bare `eq` + /// leaf, the same collapse `parseAnd`/`parseOr` already do for a + /// one-element and/or chain - lets a one-value `in` use an index like + /// `eq` does, since `findIndexableLeaf`/`findCompositeMatch` never look + /// inside `or_`. An empty list, `field in ()`, is not a syntax error: + /// it desugars to an `or_` over zero leaves, which `Predicate.evaluate` + /// already folds to `false` for an empty `preds` slice - matching SQL's + /// "IN () is always false" without a special case here. + fn parseIn(self: *Parser, field: []const u8) ParseError!Predicate { + if (self.cur.kind != .lparen) return if (self.cur.kind == .eof) error.UnexpectedEnd else error.UnexpectedToken; + self.advance(); + + var list = std.ArrayList(Predicate).init(self.allocator); + while (self.cur.kind != .rparen) { + if (self.cur.kind != .word) return if (self.cur.kind == .eof) error.UnexpectedEnd else error.UnexpectedToken; + const rawValue = rowmod.Value.parseCli(self.cur.text) catch return error.InvalidValue; + const value = try rawValue.dupe(self.allocator); + self.advance(); + try list.append(.{ .eq = .{ .field = field, .value = value } }); + } + self.advance(); + + if (list.items.len == 1) return list.items[0]; + return .{ .or_ = try list.toOwnedSlice() }; + } + + /// `field between lo and hi`: desugars to `field gte lo and field lte + /// hi` (inclusive both ends, matching SQL BETWEEN). The `and` here is + /// consumed as part of this leaf's own grammar, not the outer + /// `parseAnd` binary connective, so it never nests a further `and_` + /// level - by the time control returns to the caller, `self.cur` is + /// whatever token follows `hi` (rparen/eof/"and"/"or"), decided purely + /// by having advanced past every token this leaf owns. + fn parseBetween(self: *Parser, field: []const u8) ParseError!Predicate { + if (self.cur.kind != .word) return error.UnexpectedEnd; + const rawLow = rowmod.Value.parseCli(self.cur.text) catch return error.InvalidValue; + const low = try rawLow.dupe(self.allocator); + self.advance(); + + if (!isKeyword(self.cur, "and")) return if (self.cur.kind == .eof) error.UnexpectedEnd else error.UnexpectedToken; + self.advance(); + + if (self.cur.kind != .word) return error.UnexpectedEnd; + const rawHigh = rowmod.Value.parseCli(self.cur.text) catch return error.InvalidValue; + const high = try rawHigh.dupe(self.allocator); + self.advance(); + + const bounds = try self.allocator.alloc(Predicate, 2); + bounds[0] = .{ .gte = .{ .field = field, .value = low } }; + bounds[1] = .{ .lte = .{ .field = field, .value = high } }; + return .{ .and_ = bounds }; + } +}; + +/// Parses a full `table select` predicate expression, e.g. +/// `city eq s:warsaw and (age gte i:30 or not age lt i:10)`. The returned +/// Parsed owns every slice/pointer the Predicate tree references - `text` +/// itself does not need to outlive the call. +pub fn parse(backing: Allocator, text: []const u8) ParseError!Parsed { + var arena = std.heap.ArenaAllocator.init(backing); + errdefer arena.deinit(); + const allocator = arena.allocator(); + + var p = Parser{ .lexer = .{ .src = text }, .allocator = allocator, .cur = undefined }; + p.cur = p.lexer.next(); + + const pred = try p.parseOr(); + if (p.cur.kind != .eof) return error.UnexpectedToken; + + return .{ .arena = arena, .predicate = pred }; +} + +fn evalStr(allocator: Allocator, text: []const u8, row: *const rowmod.Row) !bool { + var parsed = try parse(allocator, text); + defer parsed.deinit(); + return parsed.predicate.evaluate(row); +} + +test "parses a single condition" { + const allocator = std.testing.allocator; + var row = rowmod.Row.init(allocator); + defer row.deinit(); + try row.set("city", .{ .text = "warsaw" }); + + try std.testing.expect(try evalStr(allocator, "city eq s:warsaw", &row)); + try std.testing.expect(!try evalStr(allocator, "city eq s:krakow", &row)); +} + +test "and binds tighter than or" { + const allocator = std.testing.allocator; + var row = rowmod.Row.init(allocator); + defer row.deinit(); + try row.set("a", .{ .int = 1 }); + try row.set("b", .{ .int = 2 }); + try row.set("c", .{ .int = 99 }); + + // a eq 1 or b eq 2 and c eq 3 == (a eq 1) or ((b eq 2) and (c eq 3)) + // b eq 2 is true but c eq 3 is false, so the and-branch is false; the + // overall result must still be true because of the leading `a eq 1`. + try std.testing.expect(try evalStr(allocator, "a eq i:1 or b eq i:2 and c eq i:3", &row)); + + var row2 = rowmod.Row.init(allocator); + defer row2.deinit(); + try row2.set("a", .{ .int = 0 }); + try row2.set("b", .{ .int = 2 }); + try row2.set("c", .{ .int = 99 }); + try std.testing.expect(!try evalStr(allocator, "a eq i:1 or b eq i:2 and c eq i:3", &row2)); +} + +test "parentheses override default precedence" { + const allocator = std.testing.allocator; + var row = rowmod.Row.init(allocator); + defer row.deinit(); + try row.set("a", .{ .int = 0 }); + try row.set("b", .{ .int = 2 }); + try row.set("c", .{ .int = 5 }); + + // (a eq 1 or b eq 2) and c eq 5 - forces the or to evaluate before and. + try std.testing.expect(try evalStr(allocator, "(a eq i:1 or b eq i:2) and c eq i:5", &row)); + try std.testing.expect(!try evalStr(allocator, "(a eq i:1 or b eq i:2) and c eq i:6", &row)); +} + +test "not negates the following term" { + const allocator = std.testing.allocator; + var row = rowmod.Row.init(allocator); + defer row.deinit(); + try row.set("age", .{ .int = 20 }); + + try std.testing.expect(try evalStr(allocator, "not age eq i:10", &row)); + try std.testing.expect(!try evalStr(allocator, "not age eq i:20", &row)); + try std.testing.expect(!try evalStr(allocator, "not (age eq i:10 or age eq i:20)", &row)); +} + +test "nested parentheses and multiple not" { + const allocator = std.testing.allocator; + var row = rowmod.Row.init(allocator); + defer row.deinit(); + try row.set("x", .{ .int = 5 }); + + try std.testing.expect(try evalStr(allocator, "not not x eq i:5", &row)); + try std.testing.expect(try evalStr(allocator, "((x eq i:5))", &row)); +} +