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| 1 | +/// The query builder code of an AST after its table, such as |
| 2 | +/// `.where('id', '=', 123)` (`astToZQL` in `packages/ast-to-zql/src/ast-to-zql.ts`, |
| 3 | +/// without `redactLiterals`). The code is JS's, as the JS inspector shows it. |
| 4 | +func astToZQL(_ ast: AST) -> String { |
| 5 | + var code = "" |
| 6 | + if let condition = ast.where { |
| 7 | + var args = Set<String>() |
| 8 | + code += zqlCondition(condition, where: true, &args) |
| 9 | + } |
| 10 | + for related in ast.related ?? [] { |
| 11 | + if related.hidden == true { |
| 12 | + if let nested = related.subquery.related?.first { code += zqlRelated(nested) } |
| 13 | + } else { |
| 14 | + code += zqlRelated(related) |
| 15 | + } |
| 16 | + } |
| 17 | + // distinct and groupBy go before orderBy, which then orders their rows. |
| 18 | + if let groupBy = ast.groupBy { |
| 19 | + let columns = groupBy.map(jsStringLiteral).joined(separator: ", ") |
| 20 | + if let aggregate = ast.aggregate { |
| 21 | + code += ".groupBy(\(columns)).\(aggregate.fn.rawValue)(\(zqlAggregateArg(aggregate)))" |
| 22 | + } else { |
| 23 | + code += ".distinct(\(columns))" |
| 24 | + } |
| 25 | + } else if let distinct = ast.aggregate?.distinct { |
| 26 | + code += ".distinct(\(distinct.map(jsStringLiteral).joined(separator: ", ")))" |
| 27 | + } |
| 28 | + if let orderBy = ast.orderBy, !orderBy.isEmpty { |
| 29 | + for part in orderBy { code += ".orderBy('\(part.field)', '\(part.direction.rawValue)')" } |
| 30 | + } |
| 31 | + if let limit = ast.limit { code += ".limit(\(JSNumber.format(limit)))" } |
| 32 | + if let start = ast.start { |
| 33 | + code += |
| 34 | + ".start(\(JSONSerializer.stringify(.object(start.row)))" |
| 35 | + + (start.exclusive ? "" : ", { inclusive: true }") + ")" |
| 36 | + } |
| 37 | + // A count of the distinct values ends the chain. |
| 38 | + if ast.aggregate?.distinct != nil { code += ".count()" } |
| 39 | + return code |
| 40 | +} |
| 41 | + |
| 42 | +/// Whether a subquery has more than a table: JS tests these properties' |
| 43 | +/// truthiness, so an empty ordering counts and a limit of 0 doesn't. |
| 44 | +private func hasSubqueryProps(_ ast: AST) -> Bool { |
| 45 | + ast.where != nil || !(ast.related ?? []).isEmpty || ast.orderBy != nil |
| 46 | + || (ast.limit.map { $0 != 0 && !$0.isNaN } ?? false) |
| 47 | +} |
| 48 | + |
| 49 | +/// `wrap`: `code`, a builder-callback expression, at the top level of a |
| 50 | +/// `.where` (a callback of its own) or inside a callback (its names join the |
| 51 | +/// enclosing callback's). |
| 52 | +private func zqlWrap( |
| 53 | + _ isWhere: Bool, _ args: inout Set<String>, _ needed: [String], _ code: String |
| 54 | +) -> String { |
| 55 | + if isWhere { |
| 56 | + let names = Set(needed).sorted(by: StringCompare.utf16Less).joined(separator: ", ") |
| 57 | + return ".where(({\(names)}) => \(code))" |
| 58 | + } |
| 59 | + args.formUnion(needed) |
| 60 | + return code |
| 61 | +} |
| 62 | + |
| 63 | +private func zqlCondition( |
| 64 | + _ condition: AST.Condition, where isWhere: Bool, _ args: inout Set<String> |
| 65 | +) -> String { |
| 66 | + let prefix = isWhere ? ".where" : "cmp" |
| 67 | + switch condition { |
| 68 | + case .simple(let op, let left, let right): |
| 69 | + let leftCode = zqlValue(left) |
| 70 | + let rightCode = zqlValue(right) |
| 71 | + let argsCode = |
| 72 | + op == .eq ? "\(leftCode), \(rightCode)" : "\(leftCode), '\(op.rawValue)', \(rightCode)" |
| 73 | + if case .json = left { |
| 74 | + // A JSON path operand only exists through the expression builder's `json()`. |
| 75 | + return zqlWrap(isWhere, &args, ["cmp", "json"], "cmp(\(argsCode))") |
| 76 | + } |
| 77 | + return "\(prefix)(\(argsCode))" |
| 78 | + case .and(let conditions), .or(let conditions): |
| 79 | + let type = condition.isAnd ? "and" : "or" |
| 80 | + if conditions.count == 1 { return zqlCondition(conditions[0], where: isWhere, &args) } |
| 81 | + if condition.isAnd { |
| 82 | + let parts = conditions.map { zqlCondition($0, where: isWhere, &args) } |
| 83 | + if isWhere { return parts.joined() } |
| 84 | + args.insert("and") |
| 85 | + return "and(" + parts.joined(separator: ", ") + ")" |
| 86 | + } |
| 87 | + // An OR gets a callback: of its own at the top level, the enclosing one |
| 88 | + // inside a callback. |
| 89 | + var own = Set<String>() |
| 90 | + let code: String |
| 91 | + if isWhere { |
| 92 | + code = conditions.map { zqlCondition($0, where: false, &own) }.joined(separator: ", ") |
| 93 | + } else { |
| 94 | + code = conditions.map { zqlCondition($0, where: false, &args) }.joined(separator: ", ") |
| 95 | + own = args |
| 96 | + } |
| 97 | + return zqlWrap(isWhere, &args, Array(own) + ["cmp", type], "\(type)(\(code))") |
| 98 | + case .correlatedSubquery(let related, let op, let flip, let scalar): |
| 99 | + let relationship = zqlRelationshipName(related) |
| 100 | + let next = nextExistsSubquery(related) |
| 101 | + let props = hasSubqueryProps(next) |
| 102 | + var options: [String] = [] |
| 103 | + if let flip { options.append("flip: \(flip)") } |
| 104 | + if let scalar { options.append("scalar: \(scalar)") } |
| 105 | + let optionsCode = options.isEmpty ? "" : ", {\(options.joined(separator: ", "))}" |
| 106 | + let subquery = props ? ", q => q\(astToZQL(next))" : "" |
| 107 | + switch op { |
| 108 | + case .exists: |
| 109 | + if isWhere { return ".whereExists('\(relationship)'\(subquery)\(optionsCode))" } |
| 110 | + args.insert("exists") |
| 111 | + return "exists('\(relationship)'\(subquery)\(optionsCode))" |
| 112 | + case .notExists: |
| 113 | + return zqlWrap( |
| 114 | + isWhere, &args, ["exists", "not"], |
| 115 | + "not(exists('\(relationship)'\(subquery)\(optionsCode)))") |
| 116 | + } |
| 117 | + } |
| 118 | +} |
| 119 | + |
| 120 | +extension AST.Condition { |
| 121 | + fileprivate var isAnd: Bool { |
| 122 | + if case .and = self { return true } |
| 123 | + return false |
| 124 | + } |
| 125 | +} |
| 126 | + |
| 127 | +/// `getNextExistsSubquery`: an `exists` over a junction edge has both hops |
| 128 | +/// as exists conditions with the same alias; the code names the far one. |
| 129 | +private func nextExistsSubquery(_ related: AST.CorrelatedSubquery) -> AST { |
| 130 | + if case .correlatedSubquery(let inner, _, _, _)? = related.subquery.where, |
| 131 | + inner.subquery.alias?.contains(subqueryAliasPrefix + "zhidden_") == true |
| 132 | + { |
| 133 | + return nextExistsSubquery(inner) |
| 134 | + } |
| 135 | + return related.subquery |
| 136 | +} |
| 137 | + |
| 138 | +private func zqlRelationshipName(_ related: AST.CorrelatedSubquery) -> String { |
| 139 | + let alias = related.subquery.alias ?? "" |
| 140 | + return alias.hasPrefix(subqueryAliasPrefix) |
| 141 | + ? String(alias.dropFirst(subqueryAliasPrefix.count)) : alias |
| 142 | +} |
| 143 | + |
| 144 | +private func zqlRelated(_ related: AST.CorrelatedSubquery) -> String { |
| 145 | + guard let alias = related.subquery.alias else { return "" } |
| 146 | + var code = ".related('\(alias)'" |
| 147 | + if hasSubqueryProps(related.subquery) { code += ", q => q" + astToZQL(related.subquery) } |
| 148 | + return code + ")" |
| 149 | +} |
| 150 | + |
| 151 | +private func zqlValue(_ value: AST.ValuePosition) -> String { |
| 152 | + switch value { |
| 153 | + case .literal(let v): return zqlLiteral(v) |
| 154 | + case .column(let name): return "'\(name)'" |
| 155 | + case .json(let column, let path): |
| 156 | + return "json('\(column)', \(zqlPath(path)))" |
| 157 | + case .static(_, let field): |
| 158 | + switch field { |
| 159 | + case .single(let f): return "authParam('\(f)')" |
| 160 | + case .path(let fields): |
| 161 | + return "authParam([\(fields.map { "'\($0)'" }.joined(separator: ", "))])" |
| 162 | + } |
| 163 | + } |
| 164 | +} |
| 165 | + |
| 166 | +private func zqlPath(_ path: [AST.JSONPathSegment]) -> String { |
| 167 | + path.map { segment in |
| 168 | + switch segment { |
| 169 | + case .key(let k): jsStringLiteral(k) |
| 170 | + case .index(let i): String(i) |
| 171 | + } |
| 172 | + }.joined(separator: ", ") |
| 173 | +} |
| 174 | + |
| 175 | +/// `transformLiteral`: what `String()` prints, with strings quoted. |
| 176 | +private func zqlLiteral(_ value: JSONValue) -> String { |
| 177 | + switch value { |
| 178 | + case .null: "null" |
| 179 | + case .array: JSONSerializer.stringify(value) |
| 180 | + case .string(let s): jsStringLiteral(s) |
| 181 | + case .number(let n): JSNumber.format(n) |
| 182 | + case .bool(let b): b ? "true" : "false" |
| 183 | + case .object: "[object Object]" |
| 184 | + } |
| 185 | +} |
| 186 | + |
| 187 | +/// `transformAggregateArg`: nothing for a count, a column, or a callback |
| 188 | +/// that picks a leaf of a `json()` column. |
| 189 | +private func zqlAggregateArg(_ aggregate: AST.Aggregate) -> String { |
| 190 | + guard let field = aggregate.field else { return "" } |
| 191 | + let name = jsStringLiteral(field) |
| 192 | + guard let path = aggregate.path else { return name } |
| 193 | + return "({json}) => json(\(name), \(zqlPath(path)))" |
| 194 | +} |
| 195 | + |
| 196 | +/// A single-quoted JS string literal of `s`, escaped as `JSON.stringify` |
| 197 | +/// escapes it (`jsStringLiteral`). |
| 198 | +private func jsStringLiteral(_ s: String) -> String { |
| 199 | + let quoted = Array(JSONSerializer.stringify(.string(s)).unicodeScalars) |
| 200 | + var out = String.UnicodeScalarView() |
| 201 | + var i = 1 |
| 202 | + let end = quoted.count - 1 |
| 203 | + while i < end { |
| 204 | + let c = quoted[i] |
| 205 | + if c == "\\", i + 1 < end, quoted[i + 1] == "\"" { |
| 206 | + out.append("\"") |
| 207 | + i += 2 |
| 208 | + continue |
| 209 | + } |
| 210 | + if c == "'" { |
| 211 | + out.append("\\") |
| 212 | + out.append("'") |
| 213 | + } else { |
| 214 | + out.append(c) |
| 215 | + } |
| 216 | + i += 1 |
| 217 | + } |
| 218 | + return "'" + String(out) + "'" |
| 219 | +} |
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