use crate::{error::QueryCompilerError, lex::*};

/// Reflects choices which token has been seen recently.

pub enum TokenState {

OpeningParenthese(usize),

OpeningBrace(usize),

ClosingBrace(usize),

CombinedResultsKeyword(usize),

Variable(usize),

}

impl TokenState {

pub fn from_keyword(keyword: String, offset: usize) -> Option<Self> {

match keyword.as_str()

{

KEYWORD_COMBINED_RESULT =>

{

Some(TokenState::CombinedResultsKeyword(offset))

},

_ => None,

}

}

}

/// Returns the position of a required character.

///

/// - `cursor` and `end` determine which substring of `statement` should be

/// scanned.

/// - `character`: the character whose position should be returned

/// - `keyword`: relevant for constructing the error message in case the

/// character has not been found. Primarily meant for constructing an error

/// message with semantics like "expected 'combined_result' (the keyword)

/// should have been closed with '}' (the character)".

///

/// The returned offset is absolute to the entire statement, not just

/// the scanned slice.

pub fn get_mandatory_succeeding_character_position(

cursor: usize,

end: usize,

statement: &str,

character: char,

keyword: &'static str)

-> Result<usize, QueryCompilerError> {

Ok(cursor

+ statement[cursor..end]

.find(character)

.ok_or(

QueryCompilerError::MissingCharacter(

character, keyword))?)

}