feat: initial release

Assisted-by: GLM 5.3 Flash

io/csv_bench_test.go

@@ -0,0 +1,65 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package io
+
+// The A/B benchmark for the CSV read path: the legacy encoding/csv
+// reader and the hand-rolled tokenizer side by side, in one process.
+// The two sub-benchmarks alternate within every -count round, so both
+// see the same machine, and the decision reads the medians with 1 to 2
+// percent treated as noise.
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/tensor/internal/core"
+)
+
+// The A/B table: a hundred thousand rows of sixteen float64 values, in
+// the text shape SaveCSV emits, sized so the per-value work dominates
+// everything else.
+const (
+	benchCSVABRows = 100000
+	benchCSVABCols = 16
+)
+
+// benchCSVABData renders the A/B table as CSV bytes, once, before the
+// measured loops.
+func benchCSVABData(b *testing.B) []byte {
+	b.Helper()
+	var buf bytes.Buffer
+	if err := SaveCSVWriter(&buf, benchFloats(benchCSVABRows, benchCSVABCols)); err != nil {
+		b.Fatal(err)
+	}
+	return buf.Bytes()
+}
+
+// BenchmarkLoadCSVReader races the two readers over the same table.
+func BenchmarkLoadCSVReader(b *testing.B) {
+	data := benchCSVABData(b)
+	impls := []struct {
+		name string
+		load func(io.Reader, bool) (*core.Array, error)
+	}{
+		{"old", loadCSVReaderLegacy},
+		{"new", LoadCSVReader},
+	}
+	for _, impl := range impls {
+		b.Run(impl.name, func(b *testing.B) {
+			r := bytes.NewReader(data)
+			b.ReportAllocs()
+			for b.Loop() {
+				r.Reset(data)
+				a, err := impl.load(r, false)
+				if err != nil {
+					b.Fatal(err)
+				}
+				if a.Shape()[0] != benchCSVABRows || a.Shape()[1] != benchCSVABCols {
+					b.Fatalf("array came back with shape %v", a.Shape())
+				}
+			}
+		})
+	}
+}