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#[macro_use] extern crate lazy_static; extern crate serde_json; use std::collections::HashMap; use serde_json::Value; mod error; use error::Error; type Handle = fn(Vec<String>) -> String; fn has(operands: Vec<String>) -> String { format!("{} IS NOT NULL", operands[0].trim_matches('\'')) } fn has_not(operands: Vec<String>) -> String { format!("{} IS NULL", operands[0].trim_matches('\'')) } fn eq(operands: Vec<String>) -> String { format!("{} = {}", operands[0].trim_matches('\''), operands[1]) } fn not_eq(operands: Vec<String>) -> String { format!("{} <> {}", operands[0].trim_matches('\''), operands[1]) } fn gt(operands: Vec<String>) -> String { format!("{} > {}", operands[0].trim_matches('\''), operands[1]) } fn gte(operands: Vec<String>) -> String { format!("{} >= {}", operands[0].trim_matches('\''), operands[1]) } fn lt(operands: Vec<String>) -> String { format!("{} < {}", operands[0].trim_matches('\''), operands[1]) } fn lte(operands: Vec<String>) -> String { format!("{} <= {}", operands[0].trim_matches('\''), operands[1]) } fn is_in(operands: Vec<String>) -> String { let (key, values) = operands.split_first().unwrap(); format!("{} IN ({})", key.trim_matches('\''), values.join(", ")) } fn not_in(operands: Vec<String>) -> String { let (key, values) = operands.split_first().unwrap(); format!("{} NOT IN ({})", key.trim_matches('\''), values.join(", ")) } fn all(operands: Vec<String>) -> String { operands.join(" AND ") } fn any(operands: Vec<String>) -> String { operands.join(" OR ") } lazy_static! { static ref OPERATORS: HashMap<&'static str, Handle> = { let mut m = HashMap::new(); m.insert("has", has as Handle); m.insert("!has", has_not as Handle); m.insert("==", eq as Handle); m.insert("!=", not_eq as Handle); m.insert(">", gt as Handle); m.insert(">=", gte as Handle); m.insert("<", lt as Handle); m.insert("<=", lte as Handle); m.insert("in", is_in as Handle); m.insert("!in", not_in as Handle); m.insert("all", all as Handle); m.insert("any", any as Handle); m }; } pub fn to_sql(expression: &Value) -> Result<String, Error> { if !expression.is_array() { return match expression.clone() { Value::String(str) => Ok(format!("'{}'", str)), _ => { let operand: String = serde_json::to_string(&expression)?; Ok(operand) } }; } let array = expression.as_array().unwrap().as_slice(); let (operator, operands) = match array.split_first() { Some((operator, operands)) => { if operator.is_string() { (operator.as_str().unwrap(), operands) } else { return Err(Error::UnknownOperator(operator.to_string())); } } None => return Err(Error::NoOperands), }; let f = match OPERATORS.get(operator) { Some(f) => f, None => return Err(Error::UnknownOperator(operator.to_string())), }; let str_operands: Vec<String> = operands .into_iter() .filter_map(|operand| to_sql(operand).ok()) .collect(); Ok(f(str_operands)) } pub fn parse(expression: &str) -> Result<String, Error> { let value: Value = serde_json::from_str(expression)?; to_sql(&value) } #[cfg(test)] mod tests { use super::parse; #[test] fn test_existential() { assert_eq!(parse(r#"["has", "key"]"#).unwrap(), "key IS NOT NULL"); assert_eq!(parse(r#"["!has", "key"]"#).unwrap(), "key IS NULL"); } #[test] fn test_comparison() { assert_eq!(parse(r#"["==", "key", 42]"#).unwrap(), r#"key = 42"#); assert_eq!(parse(r#"["==", "key", "value"]"#).unwrap(), "key = 'value'"); assert_eq!( parse(r#"["!=", "key", "value"]"#).unwrap(), "key <> 'value'" ); assert_eq!(parse(r#"[">", "key", "value"]"#).unwrap(), "key > 'value'"); assert_eq!( parse(r#"[">=", "key", "value"]"#).unwrap(), "key >= 'value'" ); assert_eq!(parse(r#"["<", "key", "value"]"#).unwrap(), "key < 'value'"); assert_eq!( parse(r#"["<=", "key", "value"]"#).unwrap(), "key <= 'value'" ); } #[test] fn test_set_membership() { assert_eq!( parse(r#"["in", "key", "v0", "v1", "v2"]"#).unwrap(), "key IN ('v0', 'v1', 'v2')" ); assert_eq!( parse(r#"["!in", "key", "v0", "v1", "v2"]"#).unwrap(), "key NOT IN ('v0', 'v1', 'v2')" ); } #[test] fn test_combining() { assert_eq!( parse(r#"["all", ["==", "key0", "value0"], ["==", "key1", "value1"], ["==", "key2", "value2"]]"#).unwrap(), r#"key0 = 'value0' AND key1 = 'value1' AND key2 = 'value2'"# ); assert_eq!( parse(r#"["any", ["==", "key0", "value0"], ["==", "key1", "value1"], ["==", "key2", "value2"]]"#).unwrap(), r#"key0 = 'value0' OR key1 = 'value1' OR key2 = 'value2'"# ); } }