Add settings and isa command-line options to cton-util wasm. (#158)

* Add settings and isa command-line options to cton-util wasm.

* Use map_err to simplify error handling.

* Use `&*` instead of `.borrow()`.

lib/reader/src/error.rs

@@ -8,7 +8,8 @@ use std::result;
 /// The location of a `Token` or `Error`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct Location {
-    /// Line number, starting from 1.
+    /// Line number. Command-line arguments are line 0 and source file
+    /// lines start from 1.
     pub line_number: usize,
 }
 
@@ -23,7 +24,11 @@ pub struct Error {
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}: {}", self.location.line_number, self.message)
+        if self.location.line_number == 0 {
+            write!(f, "command-line arguments: {}", self.message)
+        } else {
+            write!(f, "{}: {}", self.location.line_number, self.message)
+        }
     }
 }
 

lib/reader/src/lib.rs

@@ -11,7 +11,7 @@ pub use error::{Location, Result, Error};
 pub use parser::{parse_functions, parse_test};
 pub use testcommand::{TestCommand, TestOption};
 pub use testfile::{TestFile, Details, Comment};
-pub use isaspec::IsaSpec;
+pub use isaspec::{IsaSpec, parse_options};
 pub use sourcemap::SourceMap;
 
 mod error;