feat(functions): add aggregate functions

lib/src/functions/aggregate.dart

@@ -0,0 +1,192 @@
+import 'dart:math' as math;
+
+import '../ast.dart';
+import '../evaluator.dart';
+import '../values.dart';
+import 'helpers.dart';
+
+void registerAggregate(Map<String, CellFunction> registry) {
+  registry['SUM'] = (args, ctx) {
+    var total = 0.0;
+    for (final value in ctx.numbersFrom(args)) {
+      total += value;
+    }
+    return NumberValue(total);
+  };
+
+  registry['SUMSQ'] = (args, ctx) {
+    var total = 0.0;
+    for (final value in ctx.numbersFrom(args)) {
+      total += value * value;
+    }
+    return NumberValue(total);
+  };
+
+  registry['PRODUCT'] = (args, ctx) {
+    final numbers = ctx.numbersFrom(args);
+    if (numbers.isEmpty) return const NumberValue(0);
+    return NumberValue(numbers.reduce((a, b) => a * b));
+  };
+
+  registry['MIN'] = (args, ctx) {
+    final numbers = ctx.numbersFrom(args);
+    if (numbers.isEmpty) return const NumberValue(0);
+    return NumberValue(numbers.reduce(math.min));
+  };
+
+  registry['MAX'] = (args, ctx) {
+    final numbers = ctx.numbersFrom(args);
+    if (numbers.isEmpty) return const NumberValue(0);
+    return NumberValue(numbers.reduce(math.max));
+  };
+
+  registry['SUMPRODUCT'] = (args, ctx) {
+    arity(args, 1);
+    final areas = [for (final arg in args) ctx.resolveArea(arg)];
+    final length = areas.first.cells.length;
+    for (final area in areas) {
+      if (area.cells.length != length) {
+        throw const EvalException(ErrorValue(ErrorKind.value));
+      }
+    }
+    var total = 0.0;
+    for (var i = 0; i < length; i++) {
+      var product = 1.0;
+      for (final area in areas) {
+        product *= _numeric(area.cells[i]);
+      }
+      total += product;
+    }
+    return NumberValue(total);
+  };
+
+  registry['SUMIF'] = (args, ctx) {
+    arity(args, 2, 3);
+    final range = ctx.resolveArea(args[0]).cells;
+    final criterion = ctx.eval(args[1]);
+    final sumCells = args.length == 3 ? ctx.resolveArea(args[2]).cells : range;
+    var total = 0.0;
+    final count = math.min(range.length, sumCells.length);
+    for (var i = 0; i < count; i++) {
+      if (matchesCriterion(range[i], criterion, ctx) && sumCells[i] is NumberValue) {
+        total += (sumCells[i] as NumberValue).value;
+      }
+    }
+    return NumberValue(total);
+  };
+
+  registry['COUNTIF'] = (args, ctx) {
+    arity(args, 2, 2);
+    final range = ctx.resolveArea(args[0]).cells;
+    final criterion = ctx.eval(args[1]);
+    var count = 0;
+    for (final candidate in range) {
+      if (matchesCriterion(candidate, criterion, ctx)) count++;
+    }
+    return NumberValue(count.toDouble());
+  };
+
+  registry['AVERAGEIF'] = (args, ctx) {
+    arity(args, 2, 3);
+    final range = ctx.resolveArea(args[0]).cells;
+    final criterion = ctx.eval(args[1]);
+    final valueCells = args.length == 3 ? ctx.resolveArea(args[2]).cells : range;
+    var total = 0.0;
+    var count = 0;
+    final limit = math.min(range.length, valueCells.length);
+    for (var i = 0; i < limit; i++) {
+      if (matchesCriterion(range[i], criterion, ctx) && valueCells[i] is NumberValue) {
+        total += (valueCells[i] as NumberValue).value;
+        count++;
+      }
+    }
+    if (count == 0) throw const EvalException(ErrorValue(ErrorKind.divZero));
+    return NumberValue(total / count);
+  };
+
+  registry['SUMIFS'] = (args, ctx) {
+    arity(args, 3);
+    final sumCells = ctx.resolveArea(args[0]).cells;
+    final matches = _multiCriteria(args.sublist(1), sumCells.length, ctx);
+    var total = 0.0;
+    for (final index in matches) {
+      if (sumCells[index] is NumberValue) total += (sumCells[index] as NumberValue).value;
+    }
+    return NumberValue(total);
+  };
+
+  registry['AVERAGEIFS'] = (args, ctx) {
+    arity(args, 3);
+    final valueCells = ctx.resolveArea(args[0]).cells;
+    final matches = _multiCriteria(args.sublist(1), valueCells.length, ctx);
+    var total = 0.0;
+    var count = 0;
+    for (final index in matches) {
+      if (valueCells[index] is NumberValue) {
+        total += (valueCells[index] as NumberValue).value;
+        count++;
+      }
+    }
+    if (count == 0) throw const EvalException(ErrorValue(ErrorKind.divZero));
+    return NumberValue(total / count);
+  };
+
+  registry['COUNTIFS'] = (args, ctx) {
+    arity(args, 2);
+    final first = ctx.resolveArea(args[0]).cells;
+    final matches = _multiCriteria(args, first.length, ctx);
+    return NumberValue(matches.length.toDouble());
+  };
+
+  registry['MAXIFS'] = (args, ctx) {
+    arity(args, 3);
+    final valueCells = ctx.resolveArea(args[0]).cells;
+    final matches = _multiCriteria(args.sublist(1), valueCells.length, ctx);
+    final numbers = [
+      for (final index in matches)
+        if (valueCells[index] is NumberValue) (valueCells[index] as NumberValue).value,
+    ];
+    if (numbers.isEmpty) return const NumberValue(0);
+    return NumberValue(numbers.reduce(math.max));
+  };
+
+  registry['MINIFS'] = (args, ctx) {
+    arity(args, 3);
+    final valueCells = ctx.resolveArea(args[0]).cells;
+    final matches = _multiCriteria(args.sublist(1), valueCells.length, ctx);
+    final numbers = [
+      for (final index in matches)
+        if (valueCells[index] is NumberValue) (valueCells[index] as NumberValue).value,
+    ];
+    if (numbers.isEmpty) return const NumberValue(0);
+    return NumberValue(numbers.reduce(math.min));
+  };
+}
+
+List<int> _multiCriteria(List<Expr> pairs, int length, EvalContext ctx) {
+  final ranges = <List<CellValue>>[];
+  final criteria = <CellValue>[];
+  for (var i = 0; i + 1 < pairs.length; i += 2) {
+    ranges.add(ctx.resolveArea(pairs[i]).cells);
+    criteria.add(ctx.eval(pairs[i + 1]));
+  }
+  final matches = <int>[];
+  for (var index = 0; index < length; index++) {
+    var ok = true;
+    for (var r = 0; r < ranges.length; r++) {
+      if (index >= ranges[r].length || !matchesCriterion(ranges[r][index], criteria[r], ctx)) {
+        ok = false;
+        break;
+      }
+    }
+    if (ok) matches.add(index);
+  }
+  return matches;
+}
+
+double _numeric(CellValue value) {
+  if (value is NumberValue) return value.value;
+  if (value is BooleanValue) return value.value ? 1 : 0;
+  if (value is ErrorValue) throw EvalException(value);
+  return 0;
+}