ddn.data.csv¶

High-performance CSV reader/writer with RFC 4180 compliance.

Module Declaration¶

module ddn.data.csv;

Enums¶

NewlinePolicy¶

public enum NewlinePolicy {
    DETECT,
    FORCE_CRLF,
    FORCE_LF
}

Newline policy controls how record boundaries are detected and how newlines are emitted by the writer.

Value	Description
`DETECT`	Detect CRLF and LF during reading; writer uses CRLF by default
`FORCE_CRLF`	Force CRLF (`\r\n`) handling; writer emits CRLF
`FORCE_LF`	Force LF (`\n`) handling; writer emits LF

EscapeStyle¶

public enum EscapeStyle {
    NONE,
    BACKSLASH
}

Escape style for non-RFC datasets (optional extension).

Value	Description
`NONE`	Only RFC 4180 double-quote escaping inside quoted fields
`BACKSLASH`	Treat backslash as escape for delimiter/quote/newline in unquoted fields

ErrorMode¶

public enum ErrorMode {
    PERMISSIVE,
    FAIL_FAST
}

Reader error handling mode.

Value	Description
`PERMISSIVE`	Malformed rows are skipped and errors are counted; iteration continues
`FAIL_FAST`	Stop iteration at the first error

Manifest Constants¶

DEFAULT_DELIMITER¶

enum char DEFAULT_DELIMITER = ',';

Default delimiter (RFC 4180).

DEFAULT_QUOTE¶

enum char DEFAULT_QUOTE = '"';

Default quote character (RFC 4180).

DEFAULT_DOUBLE_QUOTE¶

enum bool DEFAULT_DOUBLE_QUOTE = true;

Default: interpret doubled quotes inside quoted fields.

DEFAULT_TRIM_WHITESPACE¶

enum bool DEFAULT_TRIM_WHITESPACE = false;

Default: do not trim whitespace in unquoted fields.

DEFAULT_NEWLINE_POLICY¶

enum NewlinePolicy DEFAULT_NEWLINE_POLICY = NewlinePolicy.DETECT;

Default newline policy: detect CRLF and LF on read.

DEFAULT_ESCAPE_STYLE¶

enum EscapeStyle DEFAULT_ESCAPE_STYLE = EscapeStyle.NONE;

Default escape style: RFC only.

DEFAULT_HEADER¶

enum bool DEFAULT_HEADER = false;

Default: header row absent.

Structs¶

CsvDialect¶

public struct CsvDialect

Configuration options for CSV parsing and writing.

Fields¶

Field	Type	Default	Description
`delimiter`	`char`	`','`	Field delimiter character
`quote`	`char`	`'"'`	Quote character for fields
`doubleQuote`	`bool`	`true`	Escape quotes by doubling them
`trimWhitespace`	`bool`	`false`	Trim whitespace in unquoted fields
`newlinePolicy`	`NewlinePolicy`	`DETECT`	How to handle line endings
`escapeStyle`	`EscapeStyle`	`NONE`	Escape style (RFC or backslash)
`header`	`bool`	`false`	First row is header
`strictFieldCount`	`bool`	`false`	Enforce consistent field count
`errorMode`	`ErrorMode`	`PERMISSIVE`	Error handling mode
`collectDiagnostics`	`bool`	`false`	Collect detailed error diagnostics

Constructor¶

this(char delimiter, char quote = '"', bool doubleQuote = true, 
     bool trimWhitespace = false, NewlinePolicy newlinePolicy = NewlinePolicy.DETECT,
     EscapeStyle escapeStyle = EscapeStyle.NONE, bool header = false);

Example:

// Custom dialect with semicolon delimiter
auto dialect = CsvDialect(';');

// Full configuration
auto dialect = CsvDialect(
    ',',                      // delimiter
    '"',                      // quote character
    true,                     // doubleQuote
    false,                    // trimWhitespace
    NewlinePolicy.DETECT,     // newline detection
    EscapeStyle.NONE,         // RFC 4180 escaping only
    true                      // header row present
);

FieldView¶

struct FieldView

A view into a single CSV field. Provides zero-copy access to field data.

Methods¶

toString¶

string toString() const;

Returns the field value as a string.

Returns: The field content as a string.

RowView¶

struct RowView

A view into a CSV row. Provides access to individual fields.

Methods¶

opIndex¶

FieldView opIndex(size_t index) const;

Access a field by index.

Parameter	Description
`index`	The zero-based field index

Returns: A FieldView for the specified field.

length¶

size_t length() const;

Returns the number of fields in the row.

Returns: The field count.

Aliases¶

CsvField¶

public alias CsvField = FieldView;

Shorthand for a parsed CSV field view.

CsvRow¶

public alias CsvRow = RowView;

Shorthand for a parsed CSV row view.

CsvResultT¶

public alias CsvResultT(T) = CsvResult!T;

Shorthand for CsvResult!T.

CsvReaderOf¶

public alias CsvReaderOf(R) = CsvReader!R;

Shorthand for CsvReader!R.

CsvWriterTo¶

public alias CsvWriterTo(S) = CsvWriter!S;

Shorthand for CsvWriter!S.

Templates¶

CsvReader¶

struct CsvReader(R)

CSV reader that parses CSV data from a range or string.

Constructor¶

this(R data, CsvDialect dialect = CsvDialect.init);

Parameter	Description
`data`	The CSV data source
`dialect`	The CSV dialect configuration

Properties¶

empty¶

bool empty() const;

Returns true if there are no more rows to read.

front¶

RowView front();

Returns the current row.

stats¶

auto stats() const;

Returns parsing statistics including error count.

Methods¶

popFront¶

void popFront();

Advances to the next row.

CsvWriter¶

struct CsvWriter(S)

CSV writer that outputs CSV data to a sink.

Methods¶

putRow¶

void putRow(R)(R fields);

Writes a row of fields.

Parameter	Description
`fields`	A range of field values

Example:

auto writer = csvWriter();
writer.putRow(["name", "age", "city"]);
writer.putRow(["Alice", "30", "New York"]);

data¶

string data();

Returns the accumulated CSV data (for string-based writers).

Returns: The CSV output as a string.

CsvResult¶

struct CsvResult(T)

Result type for CSV field conversion operations.

Properties¶

isOk¶

bool isOk() const;

Returns true if the conversion succeeded.

value¶

T value() const;

Returns the converted value (only valid if isOk is true).

Functions¶

byRows¶

auto byRows(R)(R data, CsvDialect dialect = CsvDialect.init);

Creates a CSV reader that iterates over rows.

Parameter	Description
`data`	The CSV data source
`dialect`	The CSV dialect configuration

Returns: A range of RowView objects.

Example:

const csv = "name,age,city\nAlice,30,New York\nBob,25,Los Angeles\n";

auto reader = byRows(csv);
reader.popFront();  // Skip header

while (!reader.empty) {
    auto row = reader.front;
    writeln(row[0].toString());  // Print name
    reader.popFront();
}

csvWriter¶

auto csvWriter(CsvDialect dialect = CsvDialect.init);

Creates a CSV writer with string output.

Parameter	Description
`dialect`	The CSV dialect configuration

Returns: A CsvWriter instance.

Example:

auto writer = csvWriter();
writer.putRow(["name", "age", "city"]);
writer.putRow(["Alice", "30", "New York"]);
string result = writer.data;

fromCsv¶

CsvResult!T fromCsv(T)(FieldView field);

Converts a CSV field to a typed value.

Parameter	Description
`field`	The field to convert

Returns: A CsvResult!T containing the converted value or an error.

Example:

auto row = reader.front;
auto intResult = fromCsv!int(row[0]);
auto floatResult = fromCsv!double(row[1]);
auto boolResult = fromCsv!bool(row[2]);

if (intResult.isOk) {
    int value = intResult.value;
}

RFC 4180 Compliance¶

The module implements RFC 4180 with the following behaviors:

Record Delimiters: CRLF per RFC; reader detects CRLF, LF, and legacy CR
Header Row: Optional; same field count as data rows when enabled
Field Delimiter: Comma by default; configurable to other single-byte delimiters
Quoted Fields: Fields containing delimiter, quote, or newline are quoted
Quote Escaping: Doubled quotes within quoted fields
Embedded Newlines: Supported inside quoted fields
Whitespace: Spaces are data; optional trimming for unquoted fields

ddn.data.csv¶

Module Declaration¶

Enums¶

NewlinePolicy¶

EscapeStyle¶

ErrorMode¶

Manifest Constants¶

DEFAULT_DELIMITER¶

DEFAULT_QUOTE¶

DEFAULT_DOUBLE_QUOTE¶

DEFAULT_TRIM_WHITESPACE¶

DEFAULT_NEWLINE_POLICY¶

DEFAULT_ESCAPE_STYLE¶

DEFAULT_HEADER¶

Structs¶

CsvDialect¶

Fields¶

Constructor¶

FieldView¶

Methods¶

toString¶

RowView¶

Methods¶

opIndex¶

length¶

Aliases¶

CsvField¶

CsvRow¶

CsvResultT¶

CsvReaderOf¶

CsvWriterTo¶

Templates¶

CsvReader¶

Constructor¶

Properties¶

empty¶

front¶

stats¶

Methods¶

popFront¶

CsvWriter¶

Methods¶

putRow¶

data¶

CsvResult¶

Properties¶

isOk¶

value¶

Functions¶

byRows¶

csvWriter¶

fromCsv¶

RFC 4180 Compliance¶

See Also¶