From 441c02d0fb763a4726ccf7670222f17b52166b51 Mon Sep 17 00:00:00 2001
From: Sidi Liang <1467329765@qq.com>
Date: Sat, 13 Feb 2021 21:09:13 +0800
Subject: [PATCH] Library: Added core library function streq and cmp according
 to FlightGear Nasal

---
 lib.nas         |  8 ++++++++
 nasal_builtin.h | 50 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/lib.nas b/lib.nas
index 5b07b85..a8d26cb 100644
--- a/lib.nas
+++ b/lib.nas
@@ -100,6 +100,10 @@ var substr=func(str,begin,length)
 {
     return nasal_call_builtin_substr(str,begin,length);
 }
+var streq=func(a,b)
+{
+    return nasal_call_builtin_streq(a,b);
+}
 var left=func(string,length)
 {
     return nasal_call_builtin_left(string,length);
@@ -108,6 +112,10 @@ var right=func(string,length)
 {
     return nasal_call_builtin_right(string,length);
 }
+var cmp=func(a,b)
+{
+    return nasal_call_builtin_cmp(a,b);
+}
 
 var io=
 {
diff --git a/nasal_builtin.h b/nasal_builtin.h
index dab9859..3106246 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -59,8 +59,10 @@ bool       builtin_die_state;// used in builtin_die
 nasal_val* builtin_die(nasal_val*,nasal_gc&);
 nasal_val* builtin_type(nasal_val*,nasal_gc&);
 nasal_val* builtin_substr(nasal_val*,nasal_gc&);
+nasal_val* builtin_streq(nasal_val*,nasal_gc&);
 nasal_val* builtin_left(nasal_val*,nasal_gc&);
 nasal_val* builtin_right(nasal_val*,nasal_gc&);
+nasal_val* builtin_cmp(nasal_val*,nasal_gc&);
 
 void builtin_error_occurred(std::string func_name,std::string info)
 {
@@ -113,8 +115,10 @@ struct FUNC_TABLE
     {"nasal_call_builtin_die",           builtin_die},
     {"nasal_call_builtin_type",          builtin_type},
     {"nasal_call_builtin_substr",        builtin_substr},
+    {"nasal_call_builtin_streq",         builtin_streq},
     {"nasal_call_builtin_left",          builtin_left},
     {"nasal_call_builtin_right",         builtin_right},
+    {"nasal_call_builtin_cmp",           builtin_cmp},
     {"",                                 NULL}
 };
 
@@ -779,6 +783,21 @@ nasal_val* builtin_substr(nasal_val* local_scope_addr,nasal_gc& gc)
     ret_addr->set_string(tmp);
     return ret_addr;
 }
+nasal_val* builtin_streq(nasal_val* local_scope_addr,nasal_gc& gc)
+{
+    nasal_val* a_addr=in_builtin_find("a");
+    nasal_val* b_addr=in_builtin_find("b");
+    nasal_val* ret_addr=gc.gc_alloc(vm_num);
+    if(a_addr->get_type()!=vm_str || b_addr->get_type()!=vm_str)
+    {
+        ret_addr->set_number((double)0);
+        return ret_addr;
+    }
+    int ret=(a_addr->get_string()==b_addr->get_string());
+    
+    ret_addr->set_number((double)ret);
+    return ret_addr;
+}
 nasal_val* builtin_left(nasal_val* local_scope_addr,nasal_gc& gc)
 {
     nasal_val* string_addr=in_builtin_find("string");
@@ -827,4 +846,35 @@ nasal_val* builtin_right(nasal_val* local_scope_addr,nasal_gc& gc)
     ret_addr->set_string(tmp);
     return ret_addr;
 }
+nasal_val* builtin_cmp(nasal_val* local_scope_addr,nasal_gc& gc)
+{
+    nasal_val* a_addr=in_builtin_find("a");
+    nasal_val* b_addr=in_builtin_find("b");
+    if(a_addr->get_type()!=vm_str)
+    {
+        builtin_error_occurred("cmp","\"a\" must be string");
+        return NULL;
+    }
+    if(b_addr->get_type()!=vm_str)
+    {
+        builtin_error_occurred("cmp","\"b\" must be string");
+        return NULL;
+    }
+    std::string a=a_addr->get_string();
+    std::string b=b_addr->get_string();
+    int alen=a.length();
+    int blen=b.length();
+    nasal_val* ret_addr=gc.gc_alloc(vm_num);
+    for(int i=0; i<alen && i<blen; i++)
+    {
+        int diff = a[i] - b[i];
+        if(diff)
+        {
+            ret_addr->set_number((double)diff < 0 ? -1 : 1);
+            return ret_addr;
+        }
+    }
+    ret_addr->set_number(alen == blen ? 0 : (alen < blen ? -1 : 1));
+    return ret_addr;
+}
 #endif
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