drasi-core 0.4.2

Drasi Core
Documentation 
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// Copyright 2024 The Drasi Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::evaluation::functions::ScalarFunction;
use crate::evaluation::variable_value::integer::Integer;
use crate::evaluation::variable_value::VariableValue;
use crate::evaluation::{ExpressionEvaluationContext, FunctionError, FunctionEvaluationError};
use async_trait::async_trait;
use drasi_query_ast::ast;

#[derive(Debug)]
pub struct Sign {}

#[async_trait]
impl ScalarFunction for Sign {
    async fn call(
        &self,
        _context: &ExpressionEvaluationContext,
        expression: &ast::FunctionExpression,
        args: Vec<VariableValue>,
    ) -> Result<VariableValue, FunctionError> {
        if args.len() != 1 {
            return Err(FunctionError {
                function_name: expression.name.to_string(),
                error: FunctionEvaluationError::InvalidArgumentCount,
            });
        }
        match &args[0] {
            VariableValue::Null => Ok(VariableValue::Null),
            VariableValue::Integer(n) => {
                let f = match n.as_i64() {
                    Some(i) => i,
                    None => {
                        return Err(FunctionError {
                            function_name: expression.name.to_string(),
                            error: FunctionEvaluationError::OverflowError,
                        })
                    }
                };
                match f.partial_cmp(&0) {
                    Some(std::cmp::Ordering::Greater) => {
                        Ok(VariableValue::Integer(Integer::from(1)))
                    }
                    Some(std::cmp::Ordering::Less) => Ok(VariableValue::Integer(Integer::from(-1))),
                    Some(std::cmp::Ordering::Equal) => Ok(VariableValue::Integer(Integer::from(0))),
                    None => {
                        return Err(FunctionError {
                            function_name: expression.name.to_string(),
                            error: FunctionEvaluationError::OverflowError,
                        })
                    }
                }
            }
            VariableValue::Float(n) => {
                let f = match n.as_f64() {
                    Some(f) => f,
                    None => {
                        return Err(FunctionError {
                            function_name: expression.name.to_string(),
                            error: FunctionEvaluationError::OverflowError,
                        })
                    }
                };
                if f > 0.0 {
                    Ok(VariableValue::Integer(Integer::from(1)))
                } else if f < 0.0 {
                    Ok(VariableValue::Integer(Integer::from(-1)))
                } else {
                    Ok(VariableValue::Integer(Integer::from(0)))
                }
            }
            _ => Err(FunctionError {
                function_name: expression.name.to_string(),
                error: FunctionEvaluationError::InvalidArgument(0),
            }),
        }
    }
}