Add isalpha, istitle, and title APIs in str (#2357)

Author: Agent-Hellboy

integration_tests/test_str_01.py

@@ -37,6 +37,52 @@ def test_str_slice():
     # TODO:
     # assert a[0:5:-1] == ""
 
+def test_str_isalpha():
+    a: str = "helloworld"
+    b: str = "hj kl"
+    c: str = "a12(){}A"
+    d: str = " "
+    res: bool = a.isalpha()
+    res2: bool = b.isalpha()
+    res3: bool = c.isalpha()
+    res4: bool = d.isalpha()
+    assert res == True 
+    assert res2 == False
+    assert res3 == False
+    assert res4 == False
+
+   
+def test_str_title():
+    a: str = "hello world"
+    b: str = "hj'kl"
+    c: str = "hELlo wOrlD"
+    d: str = "{Hel1o}world"
+    res: str = a.title()
+    res2: str = b.title()
+    res3: str = c.title()
+    res4: str = d.title()
+    assert res == "Hello World" 
+    assert res2 == "Hj'Kl"
+    assert res3 == "Hello World"
+    assert res4 == "{Hel1O}World"
+
+def test_str_istitle():
+    a: str = "Hello World"
+    b: str = "Hj'kl"
+    c: str = "hELlo wOrlD"
+    d: str = " Hello"
+    e: str = " "
+    res: bool = a.istitle()
+    res2: bool = b.istitle()
+    res3: bool = c.istitle()
+    res4: bool = d.istitle()
+    res5: bool = e.istitle()
+    assert res == True
+    assert res2 == False 
+    assert res3 == False
+    assert res4 == True
+    assert res5 == False
+
 def test_str_repeat():
     a: str
     a = "Xyz"
@@ -88,5 +134,8 @@ def check():
     test_str_join_empty_str()
     test_str_join_empty_list()
     test_constant_str_subscript()
+    test_str_title()
+    test_str_istitle()
+    test_str_isalpha()
 
 check()

src/lpython/semantics/python_ast_to_asr.cpp

@@ -6468,6 +6468,36 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
             arg.loc = loc;
             arg.m_value = s_var;
             fn_args.push_back(al, arg);
+        } else if (attr_name == "isalpha") {
+            if (args.size() != 0) {
+                throw SemanticError("str.isalpha() takes no arguments",
+                    loc);
+            }
+            fn_call_name = "_lpython_str_isalpha";
+            ASR::call_arg_t arg;
+            arg.loc = loc;
+            arg.m_value = s_var;
+            fn_args.push_back(al, arg);
+        } else if (attr_name == "istitle") {
+            if (args.size() != 0) {
+                throw SemanticError("str.istitle() takes no arguments",
+                    loc);
+            }
+            fn_call_name = "_lpython_str_istitle";
+            ASR::call_arg_t arg;
+            arg.loc = loc;
+            arg.m_value = s_var;
+            fn_args.push_back(al, arg);
+        } else if (attr_name == "title") {
+            if (args.size() != 0) {
+                throw SemanticError("str.title() takes no arguments",
+                    loc);
+            }
+            fn_call_name = "_lpython_str_title";
+            ASR::call_arg_t arg;
+            arg.loc = loc;
+            arg.m_value = s_var;
+            fn_args.push_back(al, arg);
         } else if (attr_name == "upper") {
             if (args.size() != 0) {
                 throw SemanticError("str.upper() takes no arguments",

src/lpython/semantics/python_comptime_eval.h

@@ -82,6 +82,9 @@ struct PythonIntrinsicProcedures {
             {"_lpython_str_upper", {m_builtin, &not_implemented}},
             {"_lpython_str_join", {m_builtin, &not_implemented}},
             {"_lpython_str_find", {m_builtin, &not_implemented}},
+            {"_lpython_str_isalpha", {m_builtin, &not_implemented}},
+            {"_lpython_str_title", {m_builtin, &not_implemented}},
+            {"_lpython_str_istitle", {m_builtin, &not_implemented}},
             {"_lpython_str_rstrip", {m_builtin, &not_implemented}},
             {"_lpython_str_lstrip", {m_builtin, &not_implemented}},
             {"_lpython_str_strip", {m_builtin, &not_implemented}},

src/runtime/lpython_builtin.py

@@ -685,6 +685,72 @@ def _lpython_str_join(s:str, lis:list[str]) -> str:
         res += s + lis[i]
     return res
 
+def _lpython_str_isalpha(s: str) -> bool:
+    ch: str
+    for ch in s:
+        ch_ord: i32 = ord(ch)
+        if 65 <= ch_ord and ch_ord <= 90:
+            continue
+        if 97 <= ch_ord and ch_ord <= 122:
+            continue
+        return False
+    return True
+
+def _lpython_str_title(s: str) -> str:
+    result: str = ""
+    capitalize_next: bool = True
+    ch: str
+    for ch in s:
+        ch_ord: i32 = ord(ch)
+        if ch_ord >= 97  and ch_ord <= 122:
+            if capitalize_next:
+                result += chr(ord(ch) - ord('a') + ord('A'))
+                capitalize_next = False
+            else:
+                result += ch
+        elif ch_ord >= 65 and ch_ord <= 90:
+            if capitalize_next:
+                result += ch
+                capitalize_next = False
+            else:
+                result += chr(ord(ch) + ord('a') - ord('A'))
+        else:
+            result += ch
+            capitalize_next = True
+
+    return result
+
+def _lpython_str_istitle(s: str) -> bool:
+    length: i32 = len(s)
+
+    if length == 0:
+        return False  # Empty string is not in title case
+
+    word_start: bool = True  # Flag to track the start of a word
+    ch: str
+    only_whitespace: bool = True 
+    for ch in s:
+        if (ch == ' ' or ch == '\t' or ch == '\n') and word_start:
+            continue  # Found a space character at the start of a word
+        elif ch.isalpha() and (ord('A') <= ord(ch) and ord(ch) <= ord('Z')):
+            only_whitespace = False
+            if word_start:
+                word_start = False
+            else:
+                return False  # Found an uppercase character in the middle of a word
+
+        elif ch.isalpha() and (ord('a') <= ord(ch) and ord(ch) <= ord('z')):
+            only_whitespace = False
+            if word_start:
+                return False  # Found a lowercase character in the middle of a word
+            word_start = False
+        else:
+            word_start = True
+
+    return True if not only_whitespace else False
+
+
+
 @overload
 def _lpython_str_find(s: str, sub: str) -> i32:
     s_len :i32; sub_len :i32; flag: bool; _len: i32;

tests/reference/asr-array_01_decl-39cf894.json

@@ -6,7 +6,7 @@
     "outfile": null,
     "outfile_hash": null,
     "stdout": "asr-array_01_decl-39cf894.stdout",
-    "stdout_hash": "337d67c221f17230293b36428d0f59e687b3a1d577e9b361298e1257",
+    "stdout_hash": "1faebd012adf52a67e912023e64747cd86287bca16bcd3551011da5a",
     "stderr": null,
     "stderr_hash": null,
     "returncode": 0