SXLK2022A. 预处理器

https://hydro.ac/d/ccf/record/62691baa9f31360077e283b7

Hydro/ccf/SXLK2022A/SXLK2022A.cpp

@@ -0,0 +1,74 @@
+#include <cstdio>
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 105;
+
+int n;
+// Raw strings
+std::string s[N];
+// Defines:       <name,                <content, expanding>>
+std::unordered_map<std::string, std::pair<std::string, bool>> def;
+
+std::string dfs(std::string s) {
+    std::string r;
+
+    for (int i = 0, j; i < s.size(); i += j) {
+        for (j = 0; i + j < s.size() &&
+                    ('0' <= s[i + j] && s[i + j] <= '9' ||
+                     'a' <= s[i + j] && s[i + j] <= 'z' ||
+                     'A' <= s[i + j] && s[i + j] <= 'Z' || s[i + j] == '_');
+             j++)
+            ;
+        if (j) {
+            std::string tmp = s.substr(i, j), tmp2;
+
+            if (def.count(tmp) && !def[tmp].second) {
+                def[tmp].second = true;
+                r += dfs(def[tmp].first);
+                def[tmp].second = false;
+            } else {
+                r += tmp;
+            }
+        } else {
+            r += s[i++];
+        }
+    }
+
+    return r;
+}
+
+int main() {
+    freopen("preprocessor.in", "r", stdin);
+    freopen("preprocessor.out", "w", stdout);
+
+    cin >> n;
+    for (int i = 0; i <= n; i++) {
+        std::getline(cin, s[i]);
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (s[i][0] == '#') {  // 预处理命令
+            if (s[i].substr(1, 6) == "define") {
+                int p = s[i].find_first_of(' ', 8);
+                std::string name = s[i].substr(8, p - 8),
+                            content = s[i].substr(p + 1);
+                def[name] = std::make_pair(content, false);
+            } else {  // s[i].substr(1, 6) == "undef"
+                std::string name = s[i].substr(7);
+                def.erase(name);
+            }
+            cout << endl;
+        } else {  // 普通文本
+            cout << dfs(s[i]) << endl;
+        }
+    }
+
+    return 0;
+}