68 lines
2.4 KiB
Rust
68 lines
2.4 KiB
Rust
//! BNF grammar:
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//!
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//! ```text
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//! condition = value ("==" | ">" ...) value
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//! to = value value TO value
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//! ```
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use nom::branch::alt;
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use nom::bytes::complete::tag;
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use nom::character::complete::multispace1;
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use nom::combinator::cut;
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use nom::sequence::{terminated, tuple};
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use Condition::*;
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use crate::{parse_value, FilterCondition, IResult, Span, Token};
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub enum Condition<'a> {
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GreaterThan(Token<'a>),
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GreaterThanOrEqual(Token<'a>),
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Equal(Token<'a>),
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NotEqual(Token<'a>),
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Exists,
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LowerThan(Token<'a>),
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LowerThanOrEqual(Token<'a>),
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Between { from: Token<'a>, to: Token<'a> },
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}
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/// condition = value ("==" | ">" ...) value
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pub fn parse_condition(input: Span) -> IResult<FilterCondition> {
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let operator = alt((tag("<="), tag(">="), tag("!="), tag("<"), tag(">"), tag("=")));
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let (input, (fid, op, value)) = tuple((parse_value, operator, cut(parse_value)))(input)?;
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let condition = match *op.fragment() {
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"<=" => FilterCondition::Condition { fid, op: LowerThanOrEqual(value) },
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">=" => FilterCondition::Condition { fid, op: GreaterThanOrEqual(value) },
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"!=" => FilterCondition::Condition { fid, op: NotEqual(value) },
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"<" => FilterCondition::Condition { fid, op: LowerThan(value) },
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">" => FilterCondition::Condition { fid, op: GreaterThan(value) },
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"=" => FilterCondition::Condition { fid, op: Equal(value) },
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_ => unreachable!(),
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};
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Ok((input, condition))
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}
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/// exist = value "EXISTS"
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pub fn parse_exists(input: Span) -> IResult<FilterCondition> {
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let (input, key) = terminated(parse_value, tag("EXISTS"))(input)?;
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Ok((input, FilterCondition::Condition { fid: key, op: Exists }))
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}
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/// exist = value "NOT" WS+ "EXISTS"
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pub fn parse_not_exists(input: Span) -> IResult<FilterCondition> {
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let (input, key) = parse_value(input)?;
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let (input, _) = tuple((tag("NOT"), multispace1, tag("EXISTS")))(input)?;
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Ok((input, FilterCondition::Not(Box::new(FilterCondition::Condition { fid: key, op: Exists }))))
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}
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/// to = value value "TO" WS+ value
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pub fn parse_to(input: Span) -> IResult<FilterCondition> {
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let (input, (key, from, _, _, to)) =
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tuple((parse_value, parse_value, tag("TO"), multispace1, cut(parse_value)))(input)?;
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Ok((input, FilterCondition::Condition { fid: key, op: Between { from, to } }))
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}
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