util.go

package czds

import (
	"context"
	"io"
	"strings"
)

// slice2LowerMap converts a slice of strings to a map with lowercase keys for fast lookup.
// This is useful for case-insensitive string matching operations.
func slice2LowerMap(array []string) map[string]bool {
	out := make(map[string]bool)

	for _, s := range array {
		out[strings.ToLower(s)] = true
	}

	return out
}

// readerCtx is a context-aware io.Reader wrapper that checks for context cancellation
// before each read operation, allowing long-running reads to be interrupted.
type readerCtx struct {
	ctx context.Context
	r   io.Reader
}

// Read implements io.Reader. It checks if the context has been cancelled before
// delegating to the underlying reader, allowing the read operation to be interrupted.
func (r *readerCtx) Read(p []byte) (n int, err error) {
	if err := r.ctx.Err(); err != nil {
		return 0, err
	}
	return r.r.Read(p)
}

// newReaderCtx creates a context-aware io.Reader that can be cancelled via context.
// This allows long-running read operations to be interrupted gracefully.
func newReaderCtx(ctx context.Context, r io.Reader) io.Reader {
	return &readerCtx{ctx: ctx, r: r}
}