tlbmc/configs/expression.h

#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_CONFIGS_EXPRESSION_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_CONFIGS_EXPRESSION_H_

#include <string>

#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"

namespace milotic_tlbmc {

// Evaluates a string expression with substitution.
// The function will replace all occurrences of the sub_key with the sub_value
// and then evaluate the expression starting at the first replaced value.
// After parsing, the evaluated expression result will be concatenated to the
// prefix before the first replaced value.
//
// Example output:
//   EvaluateStrExpressionSubstitution("100 + $bus", "$bus", "10") -> "110"
//   EvaluateStrExpressionSubstitution("prefix $bus - 5 * 3 + 55 suffix",
//                                     "$bus", "6") -> "prefix 58 suffix"
absl::StatusOr<std::string> EvaluateStrExpressionSubstitution(
    absl::string_view expression, absl::string_view sub_key,
    absl::string_view sub_value);

// Evaluates a given string expression from left to right if there are numeric
// tokens.
// The expression is a space-separated list of tokens. If the first token
// is an integer, the function will attempt to parse the expression and evaluate
// until it encounters a non-numeric token or reaches the end of the
// string. If the syntax is valid, the function will return the evaluated
// expression, with any remaining tokens appended as a suffix.
//
// For example, "10 + 5 - 6 * 3 suffix" is a valid expression and will return
// "27 suffix"
//
// If the first token is not an integer, the function will not attempt to parse
// the expression and will return the expression as is.
//
// For example, "something 10 + 5" will return "something 10 + 5"
//
// The function returns an error if the expression is ill-formed:
// - The expression is empty.
// - The expression has a hanging operator
// - The expression attempts to divide by zero
absl::StatusOr<std::string> EvaluateStrExpression(absl::string_view expression);

}  // namespace milotic_tlbmc

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_CONFIGS_EXPRESSION_H_