summaryrefslogtreecommitdiffstats
path: root/src/eval_env.cc
blob: 0a53ae5bad801e8d2935f6cda379e24cc735e507 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "eval_env.h"

string BindingEnv::LookupVariable(const string& var) {
  map<string, string>::iterator i = bindings_.find(var);
  if (i != bindings_.end())
    return i->second;
  if (parent_)
    return parent_->LookupVariable(var);
  return "";
}

void BindingEnv::AddBinding(const string& key, const string& val) {
  bindings_[key] = val;
}

bool EvalString::Parse(const string& input, string* err) {
  unparsed_ = input;

  string::size_type start, end;
  start = 0;
  do {
    end = input.find('$', start);
    if (end == string::npos) {
      end = input.size();
      break;
    }
    if (end > start)
      parsed_.push_back(make_pair(input.substr(start, end - start), RAW));
    start = end + 1;
    if (start < input.size() && input[start] == '{') {
      ++start;
      for (end = start + 1; end < input.size(); ++end) {
        if (input[end] == '}')
          break;
      }
      if (end >= input.size()) {
        *err = "expected closing curly after ${";
        return false;
      }
      parsed_.push_back(make_pair(input.substr(start, end - start), SPECIAL));
      ++end;
    } else {
      for (end = start; end < input.size(); ++end) {
        char c = input[end];
        if (!(('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_'))
          break;
      }
      if (end == start) {
        *err = "expected variable after $";
        return false;
      }
      parsed_.push_back(make_pair(input.substr(start, end - start), SPECIAL));
    }
    start = end;
  } while (end < input.size());
  if (end > start)
    parsed_.push_back(make_pair(input.substr(start, end - start), RAW));

  return true;
}

string EvalString::Evaluate(Env* env) const {
  string result;
  for (TokenList::const_iterator i = parsed_.begin(); i != parsed_.end(); ++i) {
    if (i->second == RAW)
      result.append(i->first);
    else
      result.append(env->LookupVariable(i->first));
  }
  return result;
}