Add 'xo-reader/' from commit 'c46c0f1cc4'

git-subtree-dir: xo-reader
git-subtree-mainline: dacdeb2cd7
git-subtree-split: c46c0f1cc4

xo-reader/src/reader/exprstatestack.cpp

@@ -0,0 +1,71 @@
+/* file exprstatestack.cpp
+ *
+ * author: Roland Conybeare
+ */
+
+#include "exprstatestack.hpp"
+
+namespace xo {
+    namespace scm {
+        exprstate &
+        exprstatestack::top_exprstate() {
+            std::size_t z = stack_.size();
+
+            if (z == 0) {
+                throw std::runtime_error
+                    ("parser::top_exprstate: unexpected empty stack");
+            }
+
+            return *(stack_[z-1]);
+        }
+
+        void
+        exprstatestack::push_exprstate(std::unique_ptr<exprstate> exs) {
+            constexpr bool c_debug_flag = true;
+            scope log(XO_DEBUG(c_debug_flag),
+                      xtag("exs", exs.get()));
+
+            std::size_t z = stack_.size();
+
+            stack_.resize(z+1);
+
+            stack_[z] = std::move(exs);
+        }
+
+        std::unique_ptr<exprstate>
+        exprstatestack::pop_exprstate() {
+            constexpr bool c_debug_flag = true;
+            scope log(XO_DEBUG(c_debug_flag),
+                      xtag("top.exstype", top_exprstate().exs_type()));
+
+            std::size_t z = stack_.size();
+
+            if (z > 0) {
+                std::unique_ptr<exprstate> top = std::move(stack_[z-1]);
+
+                stack_.resize(z-1);
+
+                return top;
+            } else {
+                return nullptr;
+            }
+        }
+
+        void
+        exprstatestack::print(std::ostream & os) const {
+            os << "<exprstatestack"
+               << xtag("size", stack_.size())
+               << std::endl;
+
+            for (std::size_t i = 0, z = stack_.size(); i < z; ++i) {
+                os << "  [" << z-i-1 << "] "
+                   << stack_[i].get()
+                   << std::endl;
+            }
+
+            os << ">" << std::endl;
+        }
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end exprstatestack.cpp */