CSV_PARSER

Creates.io = https://crates.io/crates/csv_parser_moshkovskyi

Docs.rs = https://docs.rs/csv_parser_moshkovskyi/latest/csv_parser_moshkovskyi/

General description

This is an implementation of a basic CSV parser in Rust.

Technical description of parsing process

This project provides an efficient tool for parsing CSV files.
It supports:

• Reading CSV files and validating their structure.
• Returning structured data for further processing or analysis.

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Features

• Header Support: Automatically recognizes and processes headers.
• Field Types: Handles empty, quoted, and unquoted fields.
• Error Handling: Detects and reports incorrect CSV formatting.
• Simple Integration: Easily integrates with Rust projects for data processing tasks.

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Technical Details

The parser processes CSV files line by line. It:

1. Opens the file using std::fs::File.
2. Uses csv::ReaderBuilder to handle CSV-specific rules (headers, delimiters, etc.).
3. Iterates through rows and prints records in a structured format.

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Usage

Input File (test.csv):

"name","age","city"
"John Doe",30,"New York"
"Jane Smith",25,"Los Angeles"
"Sam Brown",22,"Chicago"

Output:

Record { 0: "Alice", 1: "30", 2: "New York" }

Record { 0: "Bob", 1: "25", 2: "San Francisco" }

Record { 0: "Charlie", 1: "35", 2: "Los Angeles" }

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Grammar

• WHITESPACE: Represents spaces, tabs, newlines, and carriage returns. Used for ignoring whitespace within the CSV file.

  WHITESPACE = _{ " " | "\t" | "\n" | "\r" }

• NEWLINE: Represents line breaks in Unix and Windows styles.

  NEWLINE = _{ "\n" | "\r\n" }

• csv: The main rule for parsing a CSV file. It allows for optional whitespace or newlines at the beginning, followed by one or more record entries separated by newlines, and optional whitespace or newlines after the last record. This rule defines that a CSV file can have leading and trailing line breaks.

  csv = { (WHITESPACE | NEWLINE)* ~ record ~ (NEWLINE ~ record)* ~ (WHITESPACE | NEWLINE)* }

• record: Defines a CSV record, which consists of one or more fields separated by commas. Each field is processed according to the field rule.

  record = { field ~ ("," ~ field)* }

• field: A field in the CSV file, which can be empty (empty_field), quoted (quoted_field), or unquoted (unquoted_field).

  field = { empty_field | quoted_field | unquoted_field }

• empty_field: Represents an empty field, indicated by a single comma without any value. This is used when a field is empty.

  empty_field = _{ "," }

• quoted_field: Represents a field enclosed in double quotes ("), allowing commas or other quotes to be included in the field. For example, "value with quotes ""inside""" will be parsed as a single field. Double quotes inside the field represent a single quote in the final value.

  quoted_field = _{ "\"" ~ (!"\"" ~ ANY | "\"" ~ "\"")* ~ "\"" }

• unquoted_field: Represents a field that is not enclosed in quotes and does not contain commas or newlines. It allows any character except delimiters (, , spaces, and NEWLINE).

  unquoted_field = _{ (!("," | NEWLINE | " ") ~ ANY)+ }

  quoted_field_with_escape: Represents a quoted field where double quotes inside the field are escaped by repeating them (""). For example, "This is a ""quoted"" field" is parsed as This is a "quoted" field.

  quoted_field_with_escape = _{ "\"" ~ (!"\"" ~ ANY | "\"" ~ "\"")* ~ "\"" }

• multi_line_field: Represents a field enclosed in quotes that can span multiple lines. The field ends when a closing quote is encountered. Line breaks inside the field are treated as part of the field's content.

  multi_line_field = _{ "\"" ~ (!"\"" ~ ANY | NEWLINE ~ ANY)* ~ "\"" }