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Use RegexSet for matching DataType #3217

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merged 2 commits into from
Nov 30, 2022
Merged

Use RegexSet for matching DataType #3217

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c608961
User RegexSet for matching DataType
Nov 29, 2022
a5f0c2b
fix PR comments
Nov 29, 2022
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43 changes: 27 additions & 16 deletions arrow-csv/src/reader.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@

use core::cmp::min;
use lazy_static::lazy_static;
use regex::{Regex, RegexBuilder};
use regex::{Regex, RegexBuilder, RegexSet};
use std::collections::HashSet;
use std::fmt;
use std::fs::File;
Expand All @@ -61,6 +61,21 @@ use csv::{ByteRecord, StringRecord};
use std::ops::Neg;

lazy_static! {
static ref REGEX_SET: RegexSet = RegexSet::new([
r"^(true)$|^(false)$", //BOOLEAN
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r"^-?((\d*\.\d+|\d+\.\d*)([eE]-?\d+)?|\d+([eE]-?\d+))$", //DECIMAL
r"^-?(\d+)$", //INTEGER
r"^\d{4}-\d\d-\d\d$", //DATE32
r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d$", //DATE64
]).unwrap();
//The order should match with REGEX_SET
static ref MATCH_DATA_TYPE: Vec<DataType> = vec![
DataType::Boolean,
DataType::Float64,
DataType::Int64,
DataType::Date32,
DataType::Date64,
];
static ref PARSE_DECIMAL_RE: Regex =
Regex::new(r"^-?(\d+\.?\d*|\d*\.?\d+)$").unwrap();
static ref DECIMAL_RE: Regex =
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Expand All @@ -79,27 +94,23 @@ lazy_static! {

/// Infer the data type of a record
fn infer_field_schema(string: &str, datetime_re: Option<Regex>) -> DataType {
let datetime_re = datetime_re.unwrap_or_else(|| DATETIME_RE.clone());
// when quoting is enabled in the reader, these quotes aren't escaped, we default to
// Utf8 for them
if string.starts_with('"') {
return DataType::Utf8;
}
let matches = REGEX_SET.matches(string).into_iter().next();
// match regex in a particular order
if BOOLEAN_RE.is_match(string) {
DataType::Boolean
} else if DECIMAL_RE.is_match(string) {
DataType::Float64
} else if INTEGER_RE.is_match(string) {
DataType::Int64
} else if DATE32_RE.is_match(string) {
DataType::Date32
} else if DATE64_RE.is_match(string) {
DataType::Date64
} else if datetime_re.is_match(string) {
DataType::Timestamp(TimeUnit::Nanosecond, None)
} else {
DataType::Utf8
match matches {
Some(ix) => MATCH_DATA_TYPE[ix].clone(),
None => {
let datetime_re = datetime_re.unwrap_or_else(|| DATETIME_RE.clone());
if datetime_re.is_match(string) {
DataType::Timestamp(TimeUnit::Nanosecond, None)
} else {
DataType::Utf8
}
}
}
}

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