feat: add filename, line and column number to error reporting

src/errors/root.zig

@@ -22,13 +22,22 @@ pub const ErrorData = struct {
 
     /// Generates an error string. `alloc` is used to create the string,
     /// the caller should call `free` on the returning slice.
-    pub fn get_error_str(self: *@This(), source_code: []const u8, alloc: std.mem.Allocator) ![]u8 {
+    pub fn get_error_str(self: *@This(), source_code: []const u8, filename: []const u8, alloc: std.mem.Allocator) ![]u8 {
         const faulty_line = get_line(source_code, self.start_position);
 
         const error_message = try std.fmt.allocPrint(alloc,
             \\Error: {s}
-            \\{s}
-        , .{ self.reason, faulty_line });
+            \\[{s}:{d}:{d}]
+            \\
+            \\ {d} | {s}
+        , .{
+            self.reason,
+            filename,
+            faulty_line.line_number,
+            faulty_line.column_number,
+            faulty_line.line_number,
+            faulty_line.line,
+        });
 
         return error_message;
     }
@@ -44,7 +53,16 @@ pub const ErrorData = struct {
     }
 };
 
-fn get_line(input: []const u8, at: usize) []const u8 {
+const LineInfo = struct {
+    line: []const u8,
+    /// 1 based
+    line_number: usize,
+    /// 1 based
+    column_number: usize,
+};
+
+fn get_line(input: []const u8, at: usize) LineInfo {
+    var line_number: usize = 1;
     var line_start: usize = 0;
     var line_end: usize = 0;
     var current_pos: usize = 0;
@@ -54,9 +72,13 @@ fn get_line(input: []const u8, at: usize) []const u8 {
     while (current_pos < cap and current_pos < at) : (current_pos += 1) {
         if (input[current_pos] == '\n' and current_pos + 1 < cap) {
             line_start = current_pos + 1;
+            line_number += 1;
         }
     }
 
+    // compute the column number
+    const column_number: usize = current_pos - line_start + 1;
+
     // search the end pos of the line
     while (current_pos < cap) : (current_pos += 1) {
         // EOF is EOL
@@ -71,7 +93,11 @@ fn get_line(input: []const u8, at: usize) []const u8 {
         }
     }
 
-    return input[line_start..line_end];
+    return .{
+        .line = input[line_start..line_end],
+        .line_number = line_number,
+        .column_number = column_number,
+    };
 }
 
 test {
@@ -83,7 +109,9 @@ test "should get a single line" {
     const at = 4;
     const output = get_line(input, at);
 
-    try std.testing.expectEqualStrings("print(hello)", output);
+    try std.testing.expectEqualStrings("print(hello)", output.line);
+    try std.testing.expectEqual(1, output.line_number);
+    try std.testing.expectEqual(5, output.column_number);
 }
 
 test "should get line from 2 lines (1)" {
@@ -91,7 +119,9 @@ test "should get line from 2 lines (1)" {
     const at = 4;
     const output = get_line(input, at);
 
-    try std.testing.expectEqualStrings("print(hello)", output);
+    try std.testing.expectEqualStrings("print(hello)", output.line);
+    try std.testing.expectEqual(1, output.line_number);
+    try std.testing.expectEqual(5, output.column_number);
 }
 
 test "should get line from 2 lines (2)" {
@@ -99,7 +129,9 @@ test "should get line from 2 lines (2)" {
     const at = 15;
     const output = get_line(input, at);
 
-    try std.testing.expectEqualStrings("print(bye)", output);
+    try std.testing.expectEqualStrings("print(bye)", output.line);
+    try std.testing.expectEqual(2, output.line_number);
+    try std.testing.expectEqual(3, output.column_number);
 }
 
 test "should get line from 2 lines (3)" {
@@ -107,7 +139,9 @@ test "should get line from 2 lines (3)" {
     const at = 15;
     const output = get_line(input, at);
 
-    try std.testing.expectEqualStrings("print(sure?)", output);
+    try std.testing.expectEqualStrings("print(sure?)", output.line);
+    try std.testing.expectEqual(2, output.line_number);
+    try std.testing.expectEqual(3, output.column_number);
 }
 
 test "should gen error message" {
@@ -118,11 +152,13 @@ test "should gen error message" {
         .start_position = 6,
         .end_position = 9,
     };
-    const out = try err.get_error_str(source, std.testing.allocator);
+    const out = try err.get_error_str(source, "repl", std.testing.allocator);
     defer std.testing.allocator.free(out);
 
     try std.testing.expectEqualStrings(
         \\Error: Invalid identifier
-        \\print(ehh)
+        \\[repl:1:7]
+        \\
+        \\ 1 | print(ehh)
     , out);
 }