datafusion_optimizer/analyzer/
function_rewrite.rs

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2// or more contributor license agreements.  See the NOTICE file
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5// to you under the Apache License, Version 2.0 (the
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8//
9//   http://www.apache.org/licenses/LICENSE-2.0
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14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18//! [`ApplyFunctionRewrites`] to replace `Expr`s with function calls (e.g `||` to array_concat`)
19
20use super::AnalyzerRule;
21use datafusion_common::config::ConfigOptions;
22use datafusion_common::tree_node::Transformed;
23use datafusion_common::{DFSchema, Result};
24
25use crate::utils::NamePreserver;
26use datafusion_expr::expr_rewriter::FunctionRewrite;
27use datafusion_expr::utils::merge_schema;
28use datafusion_expr::LogicalPlan;
29use std::sync::Arc;
30
31/// Analyzer rule that invokes [`FunctionRewrite`]s on expressions
32#[derive(Default, Debug)]
33pub struct ApplyFunctionRewrites {
34    /// Expr --> Function writes to apply
35    function_rewrites: Vec<Arc<dyn FunctionRewrite + Send + Sync>>,
36}
37
38impl ApplyFunctionRewrites {
39    pub fn new(function_rewrites: Vec<Arc<dyn FunctionRewrite + Send + Sync>>) -> Self {
40        Self { function_rewrites }
41    }
42
43    /// Rewrite a single plan, and all its expressions using the provided rewriters
44    fn rewrite_plan(
45        &self,
46        plan: LogicalPlan,
47        options: &ConfigOptions,
48    ) -> Result<Transformed<LogicalPlan>> {
49        // get schema representing all available input fields. This is used for data type
50        // resolution only, so order does not matter here
51        let mut schema = merge_schema(&plan.inputs());
52
53        if let LogicalPlan::TableScan(ts) = &plan {
54            let source_schema = DFSchema::try_from_qualified_schema(
55                ts.table_name.clone(),
56                &ts.source.schema(),
57            )?;
58            schema.merge(&source_schema);
59        }
60
61        let name_preserver = NamePreserver::new(&plan);
62
63        plan.map_expressions(|expr| {
64            let original_name = name_preserver.save(&expr);
65
66            // recursively transform the expression, applying the rewrites at each step
67            let transformed_expr =
68                expr.transform_up_with_schema(&schema, |expr, schema| {
69                    let mut result = Transformed::no(expr);
70                    for rewriter in self.function_rewrites.iter() {
71                        result = result.transform_data(|expr| {
72                            rewriter.rewrite(expr, schema, options)
73                        })?;
74                    }
75                    Ok(result)
76                })?;
77
78            Ok(transformed_expr.update_data(|expr| original_name.restore(expr)))
79        })
80    }
81}
82
83impl AnalyzerRule for ApplyFunctionRewrites {
84    fn name(&self) -> &str {
85        "apply_function_rewrites"
86    }
87
88    fn analyze(&self, plan: LogicalPlan, options: &ConfigOptions) -> Result<LogicalPlan> {
89        plan.transform_up_with_subqueries(|plan| self.rewrite_plan(plan, options))
90            .map(|res| res.data)
91    }
92}
datafusion_optimizer/analyzer/function_rewrite.rs

datafusion_optimizer/analyzer/
function_rewrite.rs
