csv

type Opener func() (io.ReadCloser, error)

type Options struct {
	// Separator and Quote are single bytes. Multi-byte separators are not
	// supported: they are rare, and supporting them would put a byte-compare in
	// the innermost loop of the scanner for every file.
	Separator byte
	Quote     byte

	// Comment, if non-empty, makes any line starting with it a comment. It is a
	// byte slice rather than a byte because "//" and "#!" are both real.
	Comment []byte

	// HasHeader treats the first record as column names.
	HasHeader bool

	// ColumnNames overrides the names, whether or not there is a header. With
	// HasHeader false and no names, columns are called column_1, column_2, …
	ColumnNames []string

	// SkipRows discards this many records before the header is read. Files with a
	// banner above the header are common enough that leaving this out means
	// telling people to preprocess with sed.
	SkipRows int

	// Schema, if set, skips inference entirely. This is the option to reach for
	// when the file is big: inference costs a read of the sample, and an explicit
	// schema also removes the risk of a column being inferred from rows that do
	// not represent it.
	Schema *dtype.Schema

	// SchemaOverrides fixes individual columns while inferring the rest. The
	// common case is one identity column that looks numeric and must not be.
	SchemaOverrides map[string]dtype.DataType

	// InferRows bounds how many records inference reads. 0 means the whole file,
	// which is exact and, on a large file, expensive.
	InferRows int

	// NullValues are the texts that mean NULL, in addition to the empty string for
	// non-string columns. Case-sensitive.
	NullValues []string

	// TruncateRaggedLines accepts records with the wrong field count: extra fields
	// are dropped, missing ones become null. Off by default, because a changed
	// field count usually means the file is not what the reader thinks it is, and
	// silently padding with nulls turns that into a data problem discovered much
	// later.
	TruncateRaggedLines bool

	// MaxRecordSize bounds one record. 0 selects the default (16 MiB).
	MaxRecordSize int
}

type Source struct {
	// contains filtered or unexported fields
}

type WriteOptions struct {
	Separator byte
	Quote     byte

	// Header writes the column names as the first record.
	Header bool

	// LineTerminator defaults to "\n". Set it to "\r\n" for consumers that need it.
	LineTerminator string

	// NullValue is the text written for a null. It defaults to the empty string,
	// which reads back as null for every type EXCEPT String — where "" is a real
	// value and the reader cannot tell the two apart.
	//
	// That asymmetry is a property of CSV, not a bug here: the format has no way to
	// distinguish an absent value from an empty one. A round trip that must
	// preserve null strings needs a sentinel on both sides — WithNullValue("\\N")
	// when writing and WithNullValues("\\N") when reading.
	NullValue string
}

type Writer struct {
	// contains filtered or unexported fields
}