Added str.zfill

Author: swamishiju

src/lpython/semantics/python_ast_to_asr.cpp

@@ -7598,6 +7598,25 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
                 value.m_value = args[0].m_value;
                 fn_args.push_back(al, value);
             }
+        } else if (attr_name == "zfill") {
+            if (args.size() != 1) {
+                throw SemanticError("str.zfill() takes one argument", loc);
+            }
+            ASR::expr_t *arg_sub = args[0].m_value;
+            ASR::ttype_t *arg_sub_type = ASRUtils::expr_type(arg_sub);
+            if (!ASRUtils::is_integer(*arg_sub_type)) {
+                throw SemanticError("str.zfill() argument must be integer", loc);
+            }
+            fn_call_name = "_lpython_str_zfill";
+            ASR::call_arg_t str;
+            str.loc = loc;
+            str.m_value = s_var;
+
+            ASR::call_arg_t width;
+            width.loc = loc;
+            width.m_value = args[0].m_value;
+            fn_args.push_back(al, str);
+            fn_args.push_back(al, width);
         } else if(attr_name.size() > 2 && attr_name[0] == 'i' && attr_name[1] == 's') {
             /*
                 String Validation Methods i.e all "is" based functions are handled here

src/lpython/semantics/python_comptime_eval.h

@@ -102,7 +102,8 @@ struct PythonIntrinsicProcedures {
             {"_lpython_str_isascii", {m_builtin, &not_implemented}},
             {"_lpython_str_isspace", {m_builtin, &not_implemented}},
             {"_lpython_str_center", {m_builtin, &not_implemented}},
-            {"_lpython_str_expandtabs", {m_builtin, &not_implemented}}
+            {"_lpython_str_expandtabs", {m_builtin, &not_implemented}},
+            {"_lpython_str_zfill", {m_builtin, &not_implemented}}
         };
     }
 

src/runtime/lpython_builtin.py

@@ -1,5 +1,6 @@
-from lpython import (i8, i16, i32, i64, f32, f64, c32, c64, overload, u8,
-                     u16, u32, u64)
+from lpython import (c32, c64, f32, f64, i8, i16, i32, i64, overload, u8, u16,
+                     u32, u64)
+
 #from sys import exit
 
 #: abs() as a generic procedure.
@@ -1135,6 +1136,21 @@ def _lpython_str_expandtabs(s: str, tabsize: i32) -> str:
 def _lpython_str_expandtabs(s: str) -> str:
     return _lpython_str_expandtabs(s, 8)
 
+def _lpython_str_zfill(s: str, width: i32) -> str:
+    print(width)
+    
+    if (width <= len(s) ):
+        return s
+    ret: str 
+    ret = "0"*(width-len(s))
+
+    if (s[0] == '+' or s[0] == '-'):
+        ret = s[0] + ret + s[1:]
+    else:
+        ret = ret + s
+
+    return ret
+
 def list(s: str) -> list[str]:
     l: list[str] = []
     i: i32