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@@ -1,33 +1,9 @@
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use std::{iter::Peekable, slice::Iter};
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+use crate::ast::{Field, KIdentifier, KNumber, KString, KValue, Select, Where};
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use crate::error::KappeError;
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use crate::token::{Token, TokenType};
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-#[derive(Debug, PartialEq)]
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-pub struct Select {
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- pub fields: Vec<Field>,
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- pub source: Identifier,
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-}
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-
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-#[derive(Debug, PartialEq)]
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-pub struct Identifier {
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- pub name: String,
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-}
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-
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-#[derive(Debug, PartialEq)]
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-pub enum Field {
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- Named(String),
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- Star,
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-}
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-
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-impl Identifier {
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- pub fn new(name: &str) -> Self {
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- Self {
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- name: name.to_string(),
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- }
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- }
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-}
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-
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pub fn parse(tokens: Vec<Token>) -> Result<Select, KappeError> {
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parse_select_expression(&mut tokens.iter().peekable())
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}
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@@ -36,9 +12,15 @@ fn parse_select_expression(tokens: &mut Peekable<Iter<Token>>) -> Result<Select,
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eat(tokens, TokenType::Select)?;
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let fields = parse_fields(tokens)?;
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eat(tokens, TokenType::From)?;
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- let source = eat(tokens, TokenType::Identfiier).and_then(|t| Ok(Identifier::new(&t.value)))?;
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+ let source = eat(tokens, TokenType::Identfiier).and_then(|t| Ok(KIdentifier::new(&t.value)))?;
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+
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+ let where_clause = parse_where_clause(tokens)?;
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- Ok(Select { fields, source })
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+ Ok(Select {
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+ fields,
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+ source,
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+ where_clause,
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+ })
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}
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fn parse_fields(tokens: &mut Peekable<Iter<Token>>) -> Result<Vec<Field>, KappeError> {
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@@ -62,6 +44,57 @@ fn parse_fields(tokens: &mut Peekable<Iter<Token>>) -> Result<Vec<Field>, KappeE
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}
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}
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+fn parse_where_clause(tokens: &mut Peekable<Iter<Token>>) -> Result<Option<Where>, KappeError> {
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+ let where_clause = if current_token_is(tokens, TokenType::Where) {
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+ eat(tokens, TokenType::Where)?;
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+
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+ let predicate = parse_predicate(tokens)?;
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+
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+ if current_token_is(tokens, TokenType::Comma) {
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+ let mut predicates: Vec<Where> = vec![];
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+ predicates.push(predicate);
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+
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+ while current_token_is(tokens, TokenType::Comma) {
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+ eat(tokens, TokenType::Comma)?;
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+ let predicate = parse_predicate(tokens)?;
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+ predicates.push(predicate);
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+ }
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+
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+ Some(Where::And(predicates))
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+ } else {
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+ Some(predicate)
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+ }
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+ } else {
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+ None
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+ };
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+
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+ Ok(where_clause)
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+}
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+
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+fn parse_predicate(tokens: &mut Peekable<Iter<Token>>) -> Result<Where, KappeError> {
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+ let field = eat(tokens, TokenType::Identfiier)?;
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+ let field = KValue::Identifier(KIdentifier::new(&field.value));
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+
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+ eat(tokens, TokenType::Equals)?;
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+
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+ let value: KValue = if current_token_is(tokens, TokenType::String) {
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+ let token = eat(tokens, TokenType::String)?;
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+ Ok(KValue::String(KString::new(&token.value)))
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+ } else if current_token_is(tokens, TokenType::Number) {
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+ let token = eat(tokens, TokenType::Number)?;
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+ match token.value.parse::<f32>() {
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+ Ok(n) => Ok(KValue::Number(KNumber::new(n))),
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+ Err(_) => Err(KappeError::new("Error converting number to f32")),
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+ }
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+ } else {
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+ Err(KappeError::new(
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+ "Invalid token on right-hand side of equals sign",
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+ ))
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+ }?;
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+
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+ Ok(Where::Equals(field, value))
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+}
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+
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fn current_token_is(tokens: &mut Peekable<Iter<Token>>, token_type: TokenType) -> bool {
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match tokens.peek() {
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Some(t) => t.token_type == token_type,
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@@ -104,7 +137,8 @@ mod tests {
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_parse("SELECT * FROM index").unwrap(),
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Select {
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fields: vec![Field::Star],
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- source: Identifier::new("index")
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+ source: KIdentifier::new("index"),
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+ where_clause: None
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},
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)
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}
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@@ -115,7 +149,8 @@ mod tests {
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_parse("SELECT field FROM index").unwrap(),
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Select {
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fields: vec![Field::Named("field".to_string())],
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- source: Identifier::new("index")
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+ source: KIdentifier::new("index"),
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+ where_clause: None
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},
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)
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}
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@@ -129,7 +164,60 @@ mod tests {
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Field::Named("field_one".to_string()),
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Field::Named("field_two".to_string())
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],
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- source: Identifier::new("index")
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+ source: KIdentifier::new("index"),
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+ where_clause: None
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+ },
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+ )
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+ }
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+
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+ #[test]
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+ fn it_parses_a_select_with_a_single_predicate_where_clause() {
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+ assert_eq!(
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+ _parse("SELECT * FROM index WHERE field = \"hello\"").unwrap(),
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+ Select {
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+ fields: vec![Field::Star],
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+ source: KIdentifier::new("index"),
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+ where_clause: Some(Where::Equals(
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+ KValue::Identifier(KIdentifier::new("field")),
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+ KValue::String(KString::new("hello")),
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+ ))
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+ },
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+ )
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+ }
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+
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+ #[test]
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+ fn it_parses_a_select_with_a_numeric_predicate() {
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+ assert_eq!(
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+ _parse("SELECT * FROM index WHERE field = 123").unwrap(),
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+ Select {
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+ fields: vec![Field::Star],
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+ source: KIdentifier::new("index"),
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+ where_clause: Some(Where::Equals(
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+ KValue::Identifier(KIdentifier::new("field")),
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+ KValue::Number(KNumber::new(123.0)),
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+ ))
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+ },
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+ )
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+ }
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+
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+ #[test]
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+ fn it_parses_a_select_with_a_multiple_predicate_where_clause() {
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+ assert_eq!(
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+ _parse("SELECT * FROM index WHERE field_one = \"hello\", field_two = \"world\"")
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+ .unwrap(),
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+ Select {
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+ fields: vec![Field::Star],
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+ source: KIdentifier::new("index"),
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+ where_clause: Some(Where::And(vec![
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+ Where::Equals(
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+ KValue::Identifier(KIdentifier::new("field_one")),
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+ KValue::String(KString::new("hello")),
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+ ),
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+ Where::Equals(
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+ KValue::Identifier(KIdentifier::new("field_two")),
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+ KValue::String(KString::new("world")),
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+ )
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+ ]))
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},
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)
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}
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