gtfs/internal/csv

RFC 4180 compliant CSV parser for GTFS files

This module provides CSV parsing following the GTFS specification:

UTF-8 encoded (BOM acceptable but ignored)
Fields may be quoted with double quotes
Double quotes in fields are escaped as “”
CRLF or LF line endings are accepted
First row contains field names (headers)

Source: GTFS reference.md - File Requirements

Types

CsvRow

A parsed CSV row as a dictionary of field names to values

pub type CsvRow =
  dict.Dict(String, String)

ParseError

</>

Errors that can occur during CSV parsing

pub type ParseError {
  MissingRequiredField(field: String, row: Int)
  InvalidFieldValue(
    field: String,
    value: String,
    expected: String,
    row: Int,
  )
  InvalidRowFormat(row: Int, reason: String)
  InvalidUtf8(row: Int)
  QuotingError(row: Int, reason: String)
  EmptyFile
  FieldCountMismatch(row: Int, expected: Int, got: Int)
}

Constructors

MissingRequiredField(field: String, row: Int)

A required field is missing from the row

InvalidFieldValue(
  field: String,
  value: String,
  expected: String,
  row: Int,
)

A field value is invalid for its expected type

InvalidRowFormat(row: Int, reason: String)

The row format is malformed

```
InvalidUtf8(row: Int)
```
Invalid UTF-8 encoding
```
QuotingError(row: Int, reason: String)
```
Quoting error (unclosed quote, etc.)
```
EmptyFile
```
No header row found

FieldCountMismatch(row: Int, expected: Int, got: Int)

Mismatched field count

Values

get_optional

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pub fn get_optional(
  row: dict.Dict(String, String),
  field: String,
) -> option.Option(String)

Get an optional field from a row Returns None if the field is missing or empty

get_parsed

</>

pub fn get_parsed(
  row: dict.Dict(String, String),
  field: String,
  row_num: Int,
  parser: fn(String) -> Result(a, String),
) -> Result(option.Option(a), ParseError)

Get a field and parse it with a custom parser

get_required

</>

pub fn get_required(
  row: dict.Dict(String, String),
  field: String,
  row_num: Int,
) -> Result(String, ParseError)

Get a required field from a row Returns an error if the field is missing or empty

get_required_parsed

</>

pub fn get_required_parsed(
  row: dict.Dict(String, String),
  field: String,
  row_num: Int,
  parser: fn(String) -> Result(a, String),
) -> Result(a, ParseError)

Get a required field and parse it with a custom parser

get_with_default

</>

pub fn get_with_default(
  row: dict.Dict(String, String),
  field: String,
  default: a,
  parser: fn(String) -> Result(a, String),
) -> a

Get a field with a default value if missing or empty

parse

</>

pub fn parse(
  content: String,
) -> Result(List(dict.Dict(String, String)), ParseError)

Parse CSV content following RFC 4180 rules Returns a list of rows, each as a dictionary mapping field names to values

parse_bool

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pub fn parse_bool(value: String) -> Result(Bool, String)

Parse a boolean (0 = false, 1 = true)

parse_enum

</>

pub fn parse_enum(
  value: String,
  parser: fn(String) -> Result(a, Nil),
) -> Result(a, String)

Parse an enum value with a mapping function

parse_float

</>

pub fn parse_float(value: String) -> Result(Float, String)

Parse a float value

parse_int

</>

pub fn parse_int(value: String) -> Result(Int, String)

Parse an integer value

parse_non_negative_float

</>

pub fn parse_non_negative_float(
  value: String,
) -> Result(Float, String)

Parse a non-negative float

parse_non_negative_int

</>

pub fn parse_non_negative_int(
  value: String,
) -> Result(Int, String)

Parse a non-negative integer

parse_positive_int

</>

pub fn parse_positive_int(value: String) -> Result(Int, String)

Parse a positive integer

parse_raw

</>

pub fn parse_raw(
  content: String,
) -> Result(List(List(String)), ParseError)

Parse CSV content and return raw rows (list of field lists) Useful when you need the raw data without header mapping