// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_LINT_TEMPLATE_STRING_H_
#define ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_LINT_TEMPLATE_STRING_H_

#include <map>
#include <string>

namespace fidl {

using Substitutions = std::map<std::string, std::string>;

// Holds a string with named variables to replace, using a dictionary of
// key/value string pairs (map<std::string,std::string>). The variable format is
// $name or ${name}. Variables that without a matching key in the substitution
// map are left unchanged. "$$" converts to "$" without interpreting either "$"
// as part of a variable name.
//
// Example:
//   TemplateString ts("change '${ORIGINAL}' to '${REPLACEMENT}'");
//   std::string value = ts.Substitute({
//       {"ORIGINAL", prefix},
//       {"REPLACEMENT", replacement},
//   });
class TemplateString {
public:
    TemplateString(std::string str)
        : str_(str) {}

    // Constructs an empty template.
    TemplateString()
        : TemplateString("") {}

    // Returns true if the template string is not empty.
    explicit operator bool() const {
        return str_.size() > 0;
    }

    // Returns the string value after replacing all matched variables in the
    // template string with the values for the matching keys.
    // If |remove_unmatched| is true, variables without matching keys are
    // removed from the string.
    std::string Substitute(Substitutions substitutions,
                           bool remove_unmatched) const;

    // Returns the string value after replacing all matched variables in the
    // template string with the values for the matching keys.
    // Variables without matching keys are left in place.
    std::string Substitute(Substitutions substitutions) const {
        return Substitute(substitutions, false);
    }

    // Returns the template string with unreplaced variables (as given at
    // construction).
    inline const std::string& str() const {
        return str_;
    }

private:
    std::string str_;
};

} // namespace fidl

#endif // ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_LINT_TEMPLATE_STRING_H_