feat: C++ 阶段 2 - 模板函数基础

- template <class T> 函数: 捕获定义, 调用时按首参类型推断实例化
- 实例化命名: max(3,5)->max_i, max(1.5,2.5)->max_d, bigger(p1,p2)->bigger_Point
- 输出三段式布局: [声明/类] [模板实例化定义] [顶层函数]
- 类类型模板参数自动加 struct 前缀
- 多参数模板/模板类: 干净跳过并注释
- 修复: Cls a(3), b(7) 多声明符带构造参数
- 输出改为内存缓冲 (8MB) 支持重排

tools/pcc-cpp.c

@@ -36,6 +36,33 @@ static Token g_tok;
 static int g_line = 1;
 static int g_ns_open = 0;   /* namespace block depth (flattened) */
 
+/* ---------------- templates ---------------- */
+
+typedef struct TplFn {
+    char name[64];       /* template function name */
+    char tparam[32];     /* type parameter name (e.g. "T") */
+    char body[4096];     /* captured function text with T placeholder */
+    struct TplFn *next;
+} TplFn;
+static TplFn *g_tplfns = NULL;
+
+typedef struct TplInst {
+    char name[128];      /* mangled instantiated name, e.g. max_i */
+    struct TplInst *next;
+} TplInst;
+static TplInst *g_tplinsts = NULL;
+
+static int g_capture = 0;        /* capture emit() into g_cap */
+static char g_cap[4096];
+static int g_cap_len;
+static int g_emit_sect = 0;      /* 0 = decl buffer, 1 = function buffer */
+static char g_outbuf[8 * 1024 * 1024];  /* declarations (classes, globals) */
+static int g_out_len;
+static char g_fn_buf[8 * 1024 * 1024];   /* top-level function bodies */
+static int g_fn_len;
+static char g_tpl_defs[16384];   /* instantiated definitions (flushed at end) */
+static int g_tpl_defs_len;
+
 typedef struct ClassInfo {
     char name[128];
     char base[128];
@@ -355,8 +382,23 @@ static int g_out_is_word = 0;  /* last emitted char was word char */
 static void emit(const char *fmt, ...)
 {
     va_list ap;
+    int n;
     va_start(ap, fmt);
-    vfprintf(g_out, fmt, ap);
+    if (g_capture) {
+        n = vsnprintf(g_cap + g_cap_len, sizeof g_cap - g_cap_len, fmt, ap);
+        if (n > 0) g_cap_len += n;
+        if (g_cap_len >= (int)sizeof g_cap - 1) g_cap_len = sizeof g_cap - 1;
+    } else if (g_emit_sect == 1) {
+        if (g_fn_len < (int)sizeof g_fn_buf - 1) {
+            n = vsnprintf(g_fn_buf + g_fn_len,
+                          sizeof g_fn_buf - g_fn_len, fmt, ap);
+            if (n > 0) g_fn_len += n;
+        }
+    } else if (g_out_len < (int)sizeof g_outbuf - 1) {
+        n = vsnprintf(g_outbuf + g_out_len,
+                      sizeof g_outbuf - g_out_len, fmt, ap);
+        if (n > 0) g_out_len += n;
+    }
     va_end(ap);
 }
 
@@ -413,6 +455,7 @@ static void proto_emit(const char *fmt, ...)
 /* ---------------- class parsing ---------------- */
 
 static void gather_decl(char *type, int typesz, char *name, int namesz);
+static int tpl_call_check(char varcls[][128], char varname[][64], int nvars);
 
 static void parse_member_decl(const char *cls, const char *ret_type, const char *mname_in)
 {
@@ -555,6 +598,9 @@ static void parse_member_decl(const char *cls, const char *ret_type, const char
                     }
                     unread_tok(&nxt);
                 }
+                /* template function call inside a method body */
+                if (tpl_call_check(NULL, NULL, 0))
+                    continue;
                 if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "{")) { bd++; proto_emit(" {"); prev_dot = 0; next_tok(); continue; }
                 if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "}")) { bd--; if (bd > 0) proto_emit("}"); next_tok(); continue; }
                 if (g_tok.type == T_THIS) { proto_emit("this"); prev_dot = 0; next_tok(); continue; }
@@ -978,6 +1024,9 @@ static void parse_member_definition(const char *ret_type)
                 }
                 unread_tok(&nxt);
             }
+            /* template function call inside a method body */
+            if (tpl_call_check(NULL, NULL, 0))
+                continue;
             if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "{")) { depth++; emit(" {"); prev_dot = 0; next_tok(); continue; }
             if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "}")) {
                 if (depth > 0) { depth--; emit("}"); next_tok(); continue; }
@@ -1258,6 +1307,9 @@ static void parse_free_operator(const char *ret_type, const char *name)
                     }
                     unread_tok(&nxt);
                 }
+                /* template function call inside an operator body */
+                if (tpl_call_check(NULL, NULL, 0))
+                    continue;
                 if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "{")) {
                     bdepth++;
                     emit(" {");
@@ -1362,6 +1414,135 @@ static void parse_free_operator(const char *ret_type, const char *name)
     }
 }
 
+/* ---------------- templates ---------------- */
+
+/* replace standalone identifiers 'from' with 'to' in src */
+static void tpl_subst(char *dst, int dsz, const char *src,
+                      const char *from, const char *to)
+{
+    int d = 0, i = 0, fl = (int)strlen(from), tl = (int)strlen(to);
+    while (src[i] && d < dsz - 1) {
+        if (!strncmp(src + i, from, fl) &&
+            (i == 0 || !(isalnum((unsigned char)src[i-1]) || src[i-1] == '_')) &&
+            !(isalnum((unsigned char)src[i+fl]) || src[i+fl] == '_')) {
+            if (d + tl < dsz - 1) {
+                memcpy(dst + d, to, tl);
+                d += tl;
+            }
+            i += fl;
+        } else {
+            dst[d++] = src[i++];
+        }
+    }
+    dst[d] = 0;
+}
+
+static TplFn *find_tplfn(const char *name)
+{
+    TplFn *p;
+    for (p = g_tplfns; p; p = p->next)
+        if (!strcmp(p->name, name)) return p;
+    return NULL;
+}
+
+static const char *type_suffix(const char *t)
+{
+    if (!strcmp(t, "int")) return "i";
+    if (!strcmp(t, "double")) return "d";
+    if (!strcmp(t, "float")) return "f";
+    if (!strcmp(t, "char")) return "c";
+    if (!strcmp(t, "long")) return "l";
+    if (!strcmp(t, "short")) return "s";
+    if (!strcmp(t, "unsigned int")) return "u";
+    return t;   /* class name */
+}
+
+/* emit (once) the instantiated definition of a template function */
+static void instantiate_tpl_fn(TplFn *tf, const char *ttype, const char *mname)
+{
+    TplInst *p;
+    for (p = g_tplinsts; p; p = p->next)
+        if (!strcmp(p->name, mname)) return;
+    p = (TplInst*)calloc(1, sizeof *p);
+    strncpy(p->name, mname, sizeof p->name - 1);
+    p->name[sizeof p->name - 1] = 0;
+    p->next = g_tplinsts;
+    g_tplinsts = p;
+    {
+        char tmp[4096], def[4096];
+        char stype[96];
+        const char *subst_type = ttype;
+        if (find_class(ttype)) {
+            snprintf(stype, sizeof stype, "struct %s", ttype);
+            subst_type = stype;
+        }
+        tpl_subst(tmp, sizeof tmp, tf->body, tf->tparam, subst_type);
+        tpl_subst(def, sizeof def, tmp, tf->name, mname);
+        {
+            int l = (int)strlen(def);
+            if (g_tpl_defs_len + l + 1 < (int)sizeof g_tpl_defs) {
+                memcpy(g_tpl_defs + g_tpl_defs_len, def, l);
+                g_tpl_defs_len += l;
+                g_tpl_defs[g_tpl_defs_len++] = '\n';
+            }
+        }
+    }
+}
+
+/* If g_tok is a template function name followed by '(', infer the
+   concrete type from the first argument and rewrite g_tok to the
+   mangled instantiation name (the def is queued in g_tpl_defs).
+   Returns 1 if handled. */
+static int tpl_call_check(char varcls[][128], char varname[][64], int nvars)
+{
+    TplFn *tf;
+    Token nxt, a1;
+    const char *ttype = "int";
+    char suffix[64];
+    char mname[128];
+
+    if (g_tok.type != T_IDENT) return 0;
+    tf = find_tplfn(g_tok.text);
+    if (!tf) return 0;
+    read_tok(&nxt);
+    if (!(nxt.type == T_PUNCT && !strcmp(nxt.text, "("))) {
+        unread_tok(&nxt);
+        return 0;
+    }
+    /* stream is now at the first argument; read it to infer the type */
+    read_tok(&a1);
+    if (a1.type == T_NUMBER) {
+        if (strchr(a1.text, '.') || strchr(a1.text, 'e') ||
+            strchr(a1.text, 'E') || strchr(a1.text, 'f') ||
+            strchr(a1.text, 'F') || strchr(a1.text, 'l'))
+            ttype = "double";
+        else
+            ttype = "int";
+    } else if (a1.type == T_CHAR) {
+        ttype = "char";
+    } else if (a1.type == T_IDENT && nvars > 0) {
+        int k;
+        ttype = "int";
+        for (k = 0; k < nvars; k++)
+            if (!strcmp(a1.text, varname[k])) {
+                ttype = varcls[k];
+                break;
+            }
+    }
+    /* restore the stream: arg back, then '(' back */
+    unread_tok(&a1);
+    unread_tok(&nxt);
+    /* g_tok is still the template name; rewrite it to the mangle */
+    strncpy(suffix, type_suffix(ttype), sizeof suffix - 1);
+    suffix[sizeof suffix - 1] = 0;
+    snprintf(mname, sizeof mname, "%s_%s", tf->name, suffix);
+    instantiate_tpl_fn(tf, ttype, mname);
+    g_tok.type = T_IDENT;
+    strncpy(g_tok.text, mname, sizeof g_tok.text - 1);
+    g_tok.text[sizeof g_tok.text - 1] = 0;
+    return 1;
+}
+
 static void parse_function(const char *ret_type, const char *name)
 {
     if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "::")) {
@@ -1405,6 +1586,9 @@ static void parse_function(const char *ret_type, const char *name)
                 }
                 unread_tok(&nxt);
             }
+            /* template function call: max(a, b) -> max_i(a, b) */
+            if (tpl_call_check(varcls, varname, nvars))
+                continue;
             if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "{")) { depth++; emit(" {"); next_tok(); continue; }
             if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "}")) {
                 if (depth > 0) { depth--; emit("}"); next_tok(); continue; }
@@ -1499,7 +1683,7 @@ static void parse_function(const char *ret_type, const char *name)
                                     if (g_tok.type == T_PUNCT &&
                                         !strcmp(g_tok.text, ")")) next_tok();
                                 }
-                                continue;
+                                goto add_decls;
                             }
                             /* plain declaration: Cls var; -> default ctor */
                             if (g_tok.type == T_PUNCT &&
@@ -1510,16 +1694,53 @@ static void parse_function(const char *ret_type, const char *name)
                         }
                     }
                 }
-                /* additional declarators: Cls a, b, c; */
+                /* additional declarators: Cls a, b(2), c; */
+              add_decls:
                 while (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ",")) {
-                    emit(", ");
                     next_tok();
                     if (g_tok.type == T_IDENT && nvars < 64) {
+                        char vn[64];
                         strncpy(varcls[nvars], clsname, 127);
                         strncpy(varname[nvars], g_tok.text, 63);
+                        strncpy(vn, g_tok.text, sizeof vn - 1);
+                        vn[sizeof vn - 1] = 0;
                         nvars++;
-                        emit(" %s", g_tok.text);
                         next_tok();
+                        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "(")) {
+                            ClassInfo *cci2 = find_class(clsname);
+                            if (cci2 && cci2->has_ctor) {
+                                /* declarator with ctor args: a(3), b(7) */
+                                emit("; struct %s %s; %s_ctor(&%s",
+                                     clsname, vn, clsname, vn);
+                                next_tok();
+                                if (g_tok.type == T_PUNCT &&
+                                    !strcmp(g_tok.text, ")")) {
+                                    emit(")");
+                                    next_tok();
+                                } else {
+                                    emit(", ");
+                                    int adepth = 0;
+                                    while (!(g_tok.type == T_PUNCT &&
+                                             !strcmp(g_tok.text, ")") &&
+                                             adepth == 0)) {
+                                        if (g_tok.type == T_EOF) break;
+                                        if (g_tok.type == T_PUNCT &&
+                                            !strcmp(g_tok.text, "(")) adepth++;
+                                        if (g_tok.type == T_PUNCT &&
+                                            !strcmp(g_tok.text, ")")) adepth--;
+                                        emit_tok();
+                                        next_tok();
+                                    }
+                                    emit(")");
+                                    if (g_tok.type == T_PUNCT &&
+                                        !strcmp(g_tok.text, ")")) next_tok();
+                                }
+                                continue;   /* look for more declarators */
+                            }
+                            emit(", %s(", vn);
+                            continue;
+                        }
+                        emit(", %s", vn);
                     }
                 }
                 continue;
@@ -1727,6 +1948,100 @@ static void gather_decl(char *type, int typesz, char *name, int namesz)
     /* no name found; caller handles */
 }
 
+/* skip a declaration up to ';' or a balanced '}' */
+static void skip_decl(void)
+{
+    int depth = 0;
+    while (!(g_tok.type == T_EOF)) {
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "{")) depth++;
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "}")) {
+            if (depth == 0) { next_tok(); return; }
+            depth--;
+        }
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ";") && depth == 0) {
+            next_tok();
+            return;
+        }
+        next_tok();
+    }
+}
+
+/* template <class T> function/class */
+static void parse_template(void)
+{
+    char tparam[32] = "T";
+    char tybuf[512], nmbuf[256];
+    int multi = 0;
+
+    next_tok();   /* '<' */
+    if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "<")) {
+        next_tok();
+        /* class T  |  typename T  |  struct T */
+        if (g_tok.type == T_CLASS || g_tok.type == T_STRUCT ||
+            (g_tok.type == T_IDENT && !strcmp(g_tok.text, "typename")))
+            next_tok();
+        if (g_tok.type == T_IDENT) {
+            strncpy(tparam, g_tok.text, sizeof tparam - 1);
+            tparam[sizeof tparam - 1] = 0;
+            next_tok();
+        }
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ",")) multi = 1;
+        /* skip to '>' */
+        while (!(g_tok.type == T_EOF)) {
+            if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ">")) break;
+            next_tok();
+        }
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ">")) next_tok();
+    } else if (g_tok.type == T_CLASS) {
+        /* template<class T> */
+        next_tok();
+        if (g_tok.type == T_IDENT) {
+            strncpy(tparam, g_tok.text, sizeof tparam - 1);
+            tparam[sizeof tparam - 1] = 0;
+            next_tok();
+        }
+        if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, ">")) next_tok();
+    }
+
+    if (multi) {
+        /* multi-parameter templates: not supported, skip declaration */
+        skip_decl();
+        emit("/* skipped multi-param template */\n");
+        return;
+    }
+
+    if (g_tok.type == T_CLASS || g_tok.type == T_STRUCT) {
+        /* template class: not yet supported, skip it cleanly */
+        skip_decl();
+        emit("/* skipped template class */\n");
+        return;
+    }
+
+    /* template function */
+    gather_decl(tybuf, sizeof tybuf, nmbuf, sizeof nmbuf);
+    if (nmbuf[0]) {
+        g_capture = 1;
+        g_cap_len = 0;
+        parse_function(tybuf[0] ? tybuf : "int", nmbuf);
+        g_capture = 0;
+        g_cap[g_cap_len] = 0;
+        {
+            TplFn *tf = (TplFn*)calloc(1, sizeof *tf);
+            strncpy(tf->name, nmbuf, sizeof tf->name - 1);
+            tf->name[sizeof tf->name - 1] = 0;
+            strncpy(tf->tparam, tparam, sizeof tf->tparam - 1);
+            tf->tparam[sizeof tf->tparam - 1] = 0;
+            strncpy(tf->body, g_cap, sizeof tf->body - 1);
+            tf->body[sizeof tf->body - 1] = 0;
+            tf->next = g_tplfns;
+            g_tplfns = tf;
+        }
+    } else {
+        skip_decl();
+        emit("/* skipped unknown template */\n");
+    }
+}
+
 static void parse_program(void)
 {
     for (;;) {
@@ -1811,9 +2126,14 @@ static void parse_program(void)
             continue;
         }
 
-        if (g_tok.type == T_USING || g_tok.type == T_TEMPLATE ||
+        if (g_tok.type == T_TEMPLATE) {
-            g_tok.type == T_INLINE || g_tok.type == T_CONSTEXPR ||
+            parse_template();
-            g_tok.type == T_FRIEND || g_tok.type == T_VIRTUAL) {
+            continue;
+        }
+
+        if (g_tok.type == T_USING || g_tok.type == T_INLINE ||
+            g_tok.type == T_CONSTEXPR || g_tok.type == T_FRIEND ||
+            g_tok.type == T_VIRTUAL) {
             next_tok();
             while (!(g_tok.type == T_EOF)) {
                 if (g_tok.type == T_PUNCT &&
@@ -1837,13 +2157,19 @@ static void parse_program(void)
             char tybuf[512], nmbuf[256];
             gather_decl(tybuf, sizeof tybuf, nmbuf, sizeof nmbuf);
             if (nmbuf[0]) {
+                int was = g_emit_sect;
+                g_emit_sect = 1;
                 parse_function(tybuf[0] ? tybuf : "int", nmbuf);
+                g_emit_sect = was;
             } else if (g_tok.type == T_EOF) {
                 break;
             } else if (g_tok.type == T_PUNCT && !strcmp(g_tok.text, "(")) {
                 /* function without return type (C style) */
+                int was = g_emit_sect;
+                g_emit_sect = 1;
                 emit("int ");
                 parse_function("int", "f");
+                g_emit_sect = was;
             } else {
                 /* global variable: type + rest */
                 if (tybuf[0]) emit("%s", tybuf);
@@ -1883,6 +2209,16 @@ int main(int argc, char **argv)
     next_tok();
     parse_program();
 
+    /* layout: [declarations/classes] [template instantiations]
+       [top-level functions] */
+    fwrite(g_outbuf, 1, g_out_len, g_out);
+    if (g_tpl_defs_len) {
+        fputc('\n', g_out);
+        fwrite(g_tpl_defs, 1, g_tpl_defs_len, g_out);
+    }
+    fputc('\n', g_out);
+    fwrite(g_fn_buf, 1, g_fn_len, g_out);
+
     fclose(g_in);
     if (g_out != stdout) fclose(g_out);
     return 0;