split some of jumble out

1 files changed, 71 insertions, 0 deletions

diff --git a/src/eval_env.cc b/src/eval_env.cc
new file mode 100644
index 0000000..172544c
--- /dev/null
+++ b/src/eval_env.cc
@@ -0,0 +1,71 @@
+#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;
+}