@sap/cds-compiler/lib/model/xprAsTree.js

CDS (Core Data Services) compiler and backends

// Create a hierarchical expression tree from an `xpr` array
//
// Replace `xpr` arrays and conditions by precedence-aware tree representations.
// The transformation is deep and destructive.
//
// Queries in expressions are _not_ traversed.
//
// Function/assoc arguments and filter conditions are
//  - traversed with expressionAsTree() and conditionAsTree(),
//  - not traversed with exprAsTree() and condAsTree()

'use strict';

const xprParser = require( '../parsers/XprTree' );

function conditionAsTree( args ) {
  args.forEach( expressionAsTree );
  return xprParser.xprAsTree( args, args, true );
}
function condAsTree( args ) {
  args.forEach( exprAsTree );
  return xprParser.xprAsTree( args, args, true );
}

function expressionAsTree( expr ) {
  if (!expr || typeof expr !== 'object')
    return expr;
  if (Array.isArray( expr )) {  // hierarchical input
    // expr.forEach( expressionAsTree );  // do it again?
    return expr;
  }
  if (expr.list)                // expression, ref
    expr.list.forEach( expressionAsTree );
  if (expr.args) {               // expression, ref
    if (Array.isArray( expr.args ) )
      expr.args.forEach(expressionAsTree);
    else
      Object.values(expr.args).forEach(expressionAsTree);
  }
  if (expr.ref)                 // expression
    expr.ref.forEach( expressionAsTree );

  // conditions: change properties
  if (expr.xpr)                 // expression
    expr.xpr = conditionAsTree( expr.xpr );
  if (expr.where)               // ref or query
    expr.where = conditionAsTree( expr.where );

  return expr;
}
function exprAsTree( expr ) {
  if (!expr || typeof expr !== 'object')
    return expr;
  if (Array.isArray( expr )) {  // hierarchical input
    // expr.forEach( exprAsTree );  // do it again?
    return expr;
  }
  if (expr.list)                // expression, ref
    expr.list.forEach( exprAsTree );
  // conditions: change properties
  if (expr.xpr)                 // expression
    expr.xpr = condAsTree( expr.xpr );
  return expr;
}

module.exports = {
  conditionAsTree,
  condAsTree,
  expressionAsTree,
  exprAsTree,
};