71 lines
1.8 KiB
Dart
71 lines
1.8 KiB
Dart
import 'annotations.dart';
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import 'query.dart';
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/// Builds a SQL `JOIN` query.
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class JoinBuilder {
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final JoinType type;
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final Query from;
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final String key, value, op, alias;
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final bool aliasAllFields;
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/// A callback to produces the expression to join against, i.e.
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/// a table name, or the result of compiling a query.
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final String Function() to;
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final List<String> additionalFields;
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JoinBuilder(this.type, this.from, this.to, this.key, this.value,
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{this.op = '=',
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this.alias,
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this.additionalFields = const [],
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this.aliasAllFields = false}) {
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assert(to != null,
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'computation of this join threw an error, and returned null.');
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}
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String get fieldName {
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var v = value;
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if (aliasAllFields) {
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v = '${alias}_$v';
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}
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var right = '${from.tableName}.$v';
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if (alias != null) right = '$alias.$v';
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return right;
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}
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String nameFor(String name) {
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if (aliasAllFields) name = '${alias}_$name';
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var right = '${from.tableName}.$name';
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if (alias != null) right = '$alias.$name';
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return right;
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}
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String compile(Set<String> trampoline) {
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var compiledTo = to();
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if (compiledTo == null) return null;
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var b = StringBuffer();
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var left = '${from.tableName}.$key';
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var right = fieldName;
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switch (type) {
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case JoinType.inner:
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b.write(' INNER JOIN');
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break;
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case JoinType.left:
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b.write(' LEFT JOIN');
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break;
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case JoinType.right:
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b.write(' RIGHT JOIN');
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break;
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case JoinType.full:
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b.write(' FULL OUTER JOIN');
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break;
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case JoinType.self:
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b.write(' SELF JOIN');
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break;
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}
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b.write(' $compiledTo');
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if (alias != null) b.write(' $alias');
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b.write(' ON $left$op$right');
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return b.toString();
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}
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}
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