Coverage Report

Created: 2024-10-13 08:39

/Users/andrewlamb/Software/datafusion/datafusion/expr/src/window_function.rs
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// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements.  See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership.  The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License.  You may obtain a copy of the License at
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//
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//   http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied.  See the License for the
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// specific language governing permissions and limitations
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// under the License.
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use datafusion_common::ScalarValue;
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use crate::{expr::WindowFunction, BuiltInWindowFunction, Expr, Literal};
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/// Create an expression to represent the `rank` window function
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pub fn rank() -> Expr {
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    Expr::WindowFunction(WindowFunction::new(BuiltInWindowFunction::Rank, vec![]))
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}
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/// Create an expression to represent the `dense_rank` window function
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pub fn dense_rank() -> Expr {
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    Expr::WindowFunction(WindowFunction::new(
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        BuiltInWindowFunction::DenseRank,
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        vec![],
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    ))
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}
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/// Create an expression to represent the `percent_rank` window function
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pub fn percent_rank() -> Expr {
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    Expr::WindowFunction(WindowFunction::new(
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        BuiltInWindowFunction::PercentRank,
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        vec![],
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    ))
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}
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/// Create an expression to represent the `cume_dist` window function
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pub fn cume_dist() -> Expr {
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    Expr::WindowFunction(WindowFunction::new(BuiltInWindowFunction::CumeDist, vec![]))
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}
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/// Create an expression to represent the `ntile` window function
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pub fn ntile(arg: Expr) -> Expr {
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    Expr::WindowFunction(WindowFunction::new(BuiltInWindowFunction::Ntile, vec![arg]))
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}
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/// Create an expression to represent the `lag` window function
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pub fn lag(
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    arg: Expr,
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    shift_offset: Option<i64>,
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    default_value: Option<ScalarValue>,
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) -> Expr {
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    let shift_offset_lit = shift_offset
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0
        .map(|v| v.lit())
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        .unwrap_or(ScalarValue::Null.lit());
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    let default_lit = default_value.unwrap_or(ScalarValue::Null).lit();
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    Expr::WindowFunction(WindowFunction::new(
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        BuiltInWindowFunction::Lag,
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        vec![arg, shift_offset_lit, default_lit],
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    ))
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}
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/// Create an expression to represent the `lead` window function
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pub fn lead(
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    arg: Expr,
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    shift_offset: Option<i64>,
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    default_value: Option<ScalarValue>,
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) -> Expr {
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    let shift_offset_lit = shift_offset
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0
        .map(|v| v.lit())
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        .unwrap_or(ScalarValue::Null.lit());
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    let default_lit = default_value.unwrap_or(ScalarValue::Null).lit();
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    Expr::WindowFunction(WindowFunction::new(
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        BuiltInWindowFunction::Lead,
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        vec![arg, shift_offset_lit, default_lit],
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    ))
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}
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/// Create an expression to represent the `nth_value` window function
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pub fn nth_value(arg: Expr, n: i64) -> Expr {
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    Expr::WindowFunction(WindowFunction::new(
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        BuiltInWindowFunction::NthValue,
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        vec![arg, n.lit()],
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    ))
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}