Add STRSTARTS and STRENDS functions (#2159)

man/rgbasm.5

@@ -653,12 +653,14 @@ The following functions take varying operands, and return strings:
 .El
 .Pp
 The following functions operate on string expressions, but return integers:
-.Bl -column "STRRFIND(str, sub)"
+.Bl -column "STRSTARTS(str, prefix)"
 .It Sy Name Ta Sy Operation
 .It Fn STRLEN str Ta Returns the number of characters in Ar str .
 .It Fn STRCMP str1 str2 Ta Compares Ar str1 No and Ar str2 No according to ASCII ordering of their characters. Returns -1 if Ar str1 No is lower than Ar str2 Ns , 1 if Ar str1 No is greater than Ar str2 Ns , or 0 if they match.
 .It Fn STRFIND str sub Ta Returns the first index of Ar sub No in Ar str Ns , or -1 if it's not present.
 .It Fn STRRFIND str sub Ta Returns the last index of Ar sub No in Ar str Ns , or -1 if it's not present.
+.It Fn STRSTARTS str prefix Ta Returns 1 if Ar str No starts with Ar prefix Ns , or 0 otherwise.
+.It Fn STRENDS str suffix Ta Returns 1 if Ar str No ends with Ar suffix Ns , or 0 otherwise.
 .It Fn BYTELEN str Ta Returns the number of bytes in Ar str . Pq Non-ASCII characters can be multiple bytes.
 .It Fn STRBYTE str idx Ta Returns the byte value at Ar idx No in Ar str .
 .It Fn INCHARMAP str Ta Returns 1 if Ar str No has an entry in the current charmap, or 0 otherwise.

src/asm/lexer.cpp

@@ -180,6 +180,7 @@ static UpperMap<int> const keywords{
     {"STRCAT",        T_(OP_STRCAT)        },
     {"STRCHAR",       T_(OP_STRCHAR)       },
     {"STRCMP",        T_(OP_STRCMP)        },
+    {"STRENDS",       T_(OP_STRENDS)       },
     {"STRFIND",       T_(OP_STRFIND)       },
     {"STRFMT",        T_(OP_STRFMT)        },
     {"STRIN",         T_(OP_STRIN)         },
@@ -189,6 +190,7 @@ static UpperMap<int> const keywords{
     {"STRRIN",        T_(OP_STRRIN)        },
     {"STRRPL",        T_(OP_STRRPL)        },
     {"STRSLICE",      T_(OP_STRSLICE)      },
+    {"STRSTARTS",     T_(OP_STRSTARTS)     },
     {"STRSUB",        T_(OP_STRSUB)        },
     {"STRUPR",        T_(OP_STRUPR)        },
 

src/asm/parser.y

@@ -296,6 +296,7 @@
 %token OP_STRCAT "STRCAT"
 %token OP_STRCHAR "STRCHAR"
 %token OP_STRCMP "STRCMP"
+%token OP_STRENDS "STRENDS"
 %token OP_STRFIND "STRFIND"
 %token OP_STRFMT "STRFMT"
 %token OP_STRIN "STRIN"
@@ -305,6 +306,7 @@
 %token OP_STRRIN "STRRIN"
 %token OP_STRRPL "STRRPL"
 %token OP_STRSLICE "STRSLICE"
+%token OP_STRSTARTS "STRSTARTS"
 %token OP_STRSUB "STRSUB"
 %token OP_STRUPR "STRUPR"
 %token OP_TAN "TAN"
@@ -1480,6 +1482,12 @@ relocexpr_no_str:
 		size_t pos = $3.rfind($5);
 		$$.makeNumber(pos != std::string::npos ? pos : -1);
 	}
+	| OP_STRSTARTS LPAREN string COMMA string RPAREN {
+		$$.makeNumber($3.starts_with($5));
+	}
+	| OP_STRENDS LPAREN string COMMA string RPAREN {
+		$$.makeNumber($3.ends_with($5));
+	}
 	| OP_STRIN LPAREN string COMMA string RPAREN {
 		warning(WARNING_OBSOLETE, "`STRIN` is deprecated; use 0-indexed `STRFIND` instead");
 		size_t pos = $3.find($5);

test/asm/strstarts-strends.asm

@@ -0,0 +1,13 @@
+
+	assert STRSTARTS("string", "str")
+	assert STRENDS("string", "ing")
+	assert !STRSTARTS("string", "stringing")
+	assert !STRENDS("string", "bowstring")
+	assert STRSTARTS("string", "string")
+	assert STRENDS("string", "string")
+	assert !STRSTARTS("", "prefix")
+	assert !STRENDS("", "suffix")
+	assert STRSTARTS("string", "")
+	assert STRENDS("string", "")
+	assert STRSTARTS("", "")
+	assert STRENDS("", "")