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#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;
}
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