Merge pull request #41 from ruifonseca/add_string_parse_float_core_method

Add String.parse_float() core method

Author: maximecb

docs/language.md

@@ -202,6 +202,7 @@ render_text("Hello world");
     -   `byte_at(byte_idx)`: Get the UTF-8 byte at the given byte index.
     -   `char_at(byte_idx)`: Get a string for the single character at the given byte index. Returns `nil` if invalid.
     -   `parse_int(radix)`: Try to parse the entire string as an integer of the given `radix`. Returns `nil` on failure.
+    -   `parse_float()`: Try to parse the entire string as a float. Returns `nil` on failure.
     -   `trim()`: Produce a new string without whitespace at the beginning or end.
     -   `upper()`: Produce a new string as the uppercase version of the string.
     -   `lower()`: Produce a new string as the lowercase version of the string.

src/runtime.rs

@@ -255,6 +255,17 @@ fn string_parse_int(actor: &mut Actor, s: Value, radix: Value) -> Result<Value,
     }
 }
 
+/// Try to parse the string as a float
+fn string_parse_float(actor: &mut Actor, s: Value) -> Result<Value, String>
+{
+    let s = unwrap_str!(s);
+
+    match s.parse::<f64>() {
+        Ok(float_val) => Ok(Value::from(float_val)),
+        Err(_) => Ok(Value::Nil),
+    }
+}
+
 /// Trim whitespace
 fn string_trim(actor: &mut Actor, s: Value) -> Result<Value, String>
 {
@@ -403,6 +414,7 @@ pub fn get_method(val: Value, method_name: &str) -> Value
     static STRING_BYTE_AT: HostFn = HostFn { name: "byte_at", f: Fn2(string_byte_at) };
     static STRING_CHAR_AT: HostFn = HostFn { name: "char_at", f: Fn2(string_char_at) };
     static STRING_PARSE_INT: HostFn = HostFn { name: "parse_int", f: Fn2(string_parse_int) };
+    static STRING_PARSE_FLOAT: HostFn = HostFn { name: "parse_float", f: Fn1(string_parse_float) };
     static STRING_TRIM: HostFn = HostFn { name: "trim", f: Fn1(string_trim) };
     static STRING_UPPER: HostFn = HostFn { name: "upper", f: Fn1(string_upper) };
     static STRING_LOWER: HostFn = HostFn { name: "lower", f: Fn1(string_lower) };
@@ -466,6 +478,7 @@ pub fn get_method(val: Value, method_name: &str) -> Value
         (Value::String(_), "byte_at") => &STRING_BYTE_AT,
         (Value::String(_), "char_at") => &STRING_CHAR_AT,
         (Value::String(_), "parse_int") => &STRING_PARSE_INT,
+        (Value::String(_), "parse_float") => &STRING_PARSE_FLOAT,
         (Value::String(_), "trim") => &STRING_TRIM,
         (Value::String(_), "upper") => &STRING_UPPER,
         (Value::String(_), "lower") => &STRING_LOWER,

tests/strings.psh

@@ -38,6 +38,26 @@ assert("not a number".parse_int(10) == nil);
 assert(" 0".parse_int(2) == nil);
 assert("0 ".parse_int(2) == nil);
 
+// Test parse_float
+assert("123".parse_float() == 123);
+assert("3.14".parse_float() == 3.14);
+assert("-3.14".parse_float() == -3.14);
+assert("2.5E10".parse_float() == 2.5E10);
+assert("2.5e10".parse_float() == 2.5e10);
+assert("2.5E-10".parse_float() == 2.5E-10);
+assert("1.e1".parse_float() == 10);
+assert("1e1".parse_float() == 10);
+assert("-1e-1".parse_float() == -0.1);
+assert("5.".parse_float() == 5);
+assert(".5".parse_float() == 0.5);
+assert("0.5".parse_float() == 0.5);
+assert("7".parse_float() == 7);
+assert("007".parse_float() == 7);
+assert(" 1.0".parse_float() == nil);
+assert("1.1 ".parse_float() == nil);
+assert("1..".parse_float() == nil);
+
+
 // Test trim
 assert("  hello  ".trim() == "hello");
 assert("\n world   \n   ".trim() == "world");