github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/sql/analyze_expr.go (about)

     1  // Copyright 2017 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package sql
    12  
    13  import (
    14  	"context"
    15  
    16  	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
    17  	"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
    18  	"github.com/cockroachdb/cockroach/pkg/sql/types"
    19  )
    20  
    21  // analyzeExpr performs semantic analysis of an expression, including:
    22  // - replacing sub-queries by a sql.subquery node;
    23  // - resolving names (optional);
    24  // - type checking (with optional type enforcement);
    25  // - normalization.
    26  // The parameters sources and IndexedVars, if both are non-nil, indicate
    27  // name resolution should be performed. The IndexedVars map will be filled
    28  // as a result.
    29  func (p *planner) analyzeExpr(
    30  	ctx context.Context,
    31  	raw tree.Expr,
    32  	source *sqlbase.DataSourceInfo,
    33  	iVarHelper tree.IndexedVarHelper,
    34  	expectedType *types.T,
    35  	requireType bool,
    36  	typingContext string,
    37  ) (tree.TypedExpr, error) {
    38  	// Perform optional name resolution.
    39  	resolved := raw
    40  	if source != nil {
    41  		var err error
    42  		resolved, err = p.resolveNames(raw, source, iVarHelper)
    43  		if err != nil {
    44  			return nil, err
    45  		}
    46  	}
    47  
    48  	// Type check.
    49  	var typedExpr tree.TypedExpr
    50  	var err error
    51  	p.semaCtx.IVarContainer = iVarHelper.Container()
    52  	if requireType {
    53  		typedExpr, err = tree.TypeCheckAndRequire(ctx, resolved, &p.semaCtx,
    54  			expectedType, typingContext)
    55  	} else {
    56  		typedExpr, err = tree.TypeCheck(ctx, resolved, &p.semaCtx, expectedType)
    57  	}
    58  	p.semaCtx.IVarContainer = nil
    59  	if err != nil {
    60  		return nil, err
    61  	}
    62  
    63  	// Normalize.
    64  	return p.txCtx.NormalizeExpr(p.EvalContext(), typedExpr)
    65  }