Implemented error messages

src/build/Build.go

@@ -7,34 +7,20 @@ import (
 
 // Build describes a compiler build.
 type Build struct {
-	Files           []string
-	WriteExecutable bool
+	Files []string
 }
 
 // New creates a new build.
 func New(files ...string) *Build {
 	return &Build{
-		Files:           files,
-		WriteExecutable: true,
+		Files: files,
 	}
 }
 
 // Run parses the input files and generates an executable file.
-func (build *Build) Run() error {
+func (build *Build) Run() (map[string]*Function, error) {
 	functions, errors := Scan(build.Files)
-	allFunctions, err := Compile(functions, errors)
-
-	if err != nil {
-		return err
-	}
-
-	if !build.WriteExecutable {
-		return nil
-	}
-
-	path := build.Executable()
-	code, data := Finalize(allFunctions)
-	return Write(path, code, data)
+	return Compile(functions, errors)
 }
 
 // Executable returns the path to the executable.

src/build/Build_test.go

@@ -1,6 +1,7 @@
 package build_test
 
 import (
+	"path/filepath"
 	"testing"
 
 	"git.akyoto.dev/cli/q/src/build"
@@ -9,16 +10,17 @@ import (
 
 func TestBuild(t *testing.T) {
 	b := build.New("../../examples/hello")
-	assert.Nil(t, b.Run())
+	_, err := b.Run()
+	assert.Nil(t, err)
 }
 
-func TestSkipExecutable(t *testing.T) {
+func TestExecutable(t *testing.T) {
 	b := build.New("../../examples/hello")
-	b.WriteExecutable = false
-	assert.Nil(t, b.Run())
+	assert.Equal(t, filepath.Base(b.Executable()), "hello")
 }
 
 func TestNonExisting(t *testing.T) {
 	b := build.New("does-not-exist")
-	assert.NotNil(t, b.Run())
+	_, err := b.Run()
+	assert.NotNil(t, err)
 }

src/build/Scan.go

@@ -8,6 +8,7 @@ import (
 
 	"git.akyoto.dev/cli/q/src/build/directory"
 	"git.akyoto.dev/cli/q/src/build/token"
+	"git.akyoto.dev/cli/q/src/errors"
 )
 
 // Scan scans the directory.
@@ -86,46 +87,141 @@ func scanFile(path string, functions chan<- *Function) error {
 	tokens := token.Tokenize(contents)
 
 	var (
+		i           = 0
 		groupLevel  = 0
 		blockLevel  = 0
-		headerStart = -1
+		nameStart   = -1
+		paramsStart = -1
 		bodyStart   = -1
 	)
 
-	for i, t := range tokens {
-		switch t.Kind {
-		case token.Identifier:
-			if blockLevel == 0 && groupLevel == 0 {
-				headerStart = i
+	for {
+		// Function name
+		for i < len(tokens) {
+			if tokens[i].Kind == token.Identifier {
+				nameStart = i
+				i++
+				break
 			}
 
-		case token.GroupStart:
-			groupLevel++
-
-		case token.GroupEnd:
-			groupLevel--
-
-		case token.BlockStart:
-			blockLevel++
-
-			if blockLevel == 1 {
-				bodyStart = i
+			if tokens[i].Kind == token.NewLine {
+				i++
+				continue
 			}
 
-		case token.BlockEnd:
-			blockLevel--
+			if tokens[i].Kind == token.EOF {
+				return nil
+			}
 
-			if blockLevel == 0 {
-				function := &Function{
-					Name: tokens[headerStart].Text(),
-					Head: tokens[headerStart:bodyStart],
-					Body: tokens[bodyStart : i+1],
+			return errors.New(errors.ExpectedFunctionName, path, tokens, i)
+		}
+
+		// Function parameters
+		for i < len(tokens) {
+			if tokens[i].Kind == token.GroupStart {
+				groupLevel++
+
+				if groupLevel == 1 {
+					paramsStart = i
 				}
 
-				functions <- function
+				i++
+				continue
 			}
-		}
-	}
 
-	return nil
+			if tokens[i].Kind == token.GroupEnd {
+				groupLevel--
+
+				if groupLevel < 0 {
+					return errors.New(errors.MissingGroupStart, path, tokens, i)
+				}
+
+				i++
+
+				if groupLevel == 0 {
+					break
+				}
+
+				continue
+			}
+
+			if tokens[i].Kind == token.EOF {
+				if groupLevel > 0 {
+					return errors.New(errors.MissingGroupEnd, path, tokens, i)
+				}
+
+				if paramsStart == -1 {
+					return errors.New(errors.ExpectedFunctionParameters, path, tokens, i)
+				}
+
+				return nil
+			}
+
+			if groupLevel > 0 {
+				i++
+				continue
+			}
+
+			return errors.New(errors.ExpectedFunctionParameters, path, tokens, i)
+		}
+
+		// Function definition
+		for i < len(tokens) {
+			if tokens[i].Kind == token.BlockStart {
+				blockLevel++
+
+				if blockLevel == 1 {
+					bodyStart = i
+				}
+
+				i++
+				continue
+			}
+
+			if tokens[i].Kind == token.BlockEnd {
+				blockLevel--
+
+				if blockLevel < 0 {
+					return errors.New(errors.MissingBlockStart, path, tokens, i)
+				}
+
+				i++
+
+				if blockLevel == 0 {
+					break
+				}
+
+				continue
+			}
+
+			if tokens[i].Kind == token.EOF {
+				if blockLevel > 0 {
+					return errors.New(errors.MissingBlockEnd, path, tokens, i)
+				}
+
+				if bodyStart == -1 {
+					return errors.New(errors.ExpectedFunctionDefinition, path, tokens, i)
+				}
+
+				return nil
+			}
+
+			if blockLevel > 0 {
+				i++
+				continue
+			}
+
+			return errors.New(errors.ExpectedFunctionDefinition, path, tokens, i)
+		}
+
+		functions <- &Function{
+			Name: tokens[nameStart].Text(),
+			Head: tokens[paramsStart:bodyStart],
+			Body: tokens[bodyStart : i+1],
+		}
+
+		nameStart = -1
+		paramsStart = -1
+		bodyStart = -1
+	}
 }

src/build/token/Kind.go

@@ -7,6 +7,9 @@ const (
 	// Invalid represents an invalid token.
 	Invalid Kind = iota
 
+	// EOF represents the end of file.
+	EOF
+
 	// NewLine represents the newline character.
 	NewLine
 
@@ -54,6 +57,7 @@ const (
 func (kind Kind) String() string {
 	return [...]string{
 		"Invalid",
+		"EOF",
 		"NewLine",
 		"Identifier",
 		"Keyword",

src/build/token/Token_test.go

@@ -35,6 +35,11 @@ func TestFunction(t *testing.T) {
 			Bytes:    []byte("}"),
 			Position: 7,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 8,
+		},
 	})
 }
 
@@ -51,6 +56,11 @@ func TestKeyword(t *testing.T) {
 			Bytes:    []byte("x"),
 			Position: 7,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 8,
+		},
 	})
 }
 
@@ -77,6 +87,11 @@ func TestArray(t *testing.T) {
 			Bytes:    []byte("]"),
 			Position: 7,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 8,
+		},
 	})
 }
 
@@ -93,6 +108,11 @@ func TestNewline(t *testing.T) {
 			Bytes:    []byte("\n"),
 			Position: 1,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 2,
+		},
 	})
 }
 
@@ -109,6 +129,11 @@ func TestNumber(t *testing.T) {
 			Bytes:    []byte("-456"),
 			Position: 4,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 8,
+		},
 	})
 }
 
@@ -140,6 +165,11 @@ func TestSeparator(t *testing.T) {
 			Bytes:    []byte("c"),
 			Position: 4,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 5,
+		},
 	})
 }
 
@@ -156,6 +186,11 @@ func TestString(t *testing.T) {
 			Bytes:    []byte(`"World"`),
 			Position: 8,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 15,
+		},
 	})
 }
 
@@ -167,6 +202,11 @@ func TestStringMultiline(t *testing.T) {
 			Bytes:    []byte("\"Hello\nWorld\""),
 			Position: 0,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 13,
+		},
 	})
 }
 
@@ -178,6 +218,11 @@ func TestStringEOF(t *testing.T) {
 			Bytes:    []byte(`"EOF`),
 			Position: 0,
 		},
+		{
+			Kind:     token.EOF,
+			Bytes:    nil,
+			Position: 4,
+		},
 	})
 }
 
@@ -195,6 +240,7 @@ func TestTokenText(t *testing.T) {
 
 func TestTokenKind(t *testing.T) {
 	assert.Equal(t, token.Invalid.String(), "Invalid")
+	assert.Equal(t, token.EOF.String(), "EOF")
 	assert.Equal(t, token.NewLine.String(), "NewLine")
 	assert.Equal(t, token.Identifier.String(), "Identifier")
 	assert.Equal(t, token.Keyword.String(), "Keyword")

src/build/token/Tokenize.go

@@ -31,6 +31,7 @@ func Tokenize(buffer []byte) List {
 			for i < len(buffer) {
 				if buffer[i] == '"' {
 					end = i + 1
+					i++
 					break
 				}
 
@@ -43,6 +44,8 @@ func Tokenize(buffer []byte) List {
 				buffer[start:end],
 			})
 
+			continue
+
 		// Parentheses start
 		case '(':
 			tokens = append(tokens, Token{GroupStart, i, groupStartBytes})
@@ -121,6 +124,7 @@ func Tokenize(buffer []byte) List {
 		i++
 	}
 
+	tokens = append(tokens, Token{EOF, i, nil})
 	return tokens
 }
 

src/cli/Build.go

@@ -11,11 +11,12 @@ import (
 // Build builds an executable.
 func Build(args []string) int {
 	b := build.New()
+	writeExecutable := true
 
 	for i := 0; i < len(args); i++ {
 		switch args[i] {
 		case "--dry":
-			b.WriteExecutable = false
+			writeExecutable = false
 
 		case "--verbose", "-v":
 			config.Verbose = true
@@ -34,7 +35,20 @@ func Build(args []string) int {
 		b.Files = append(b.Files, ".")
 	}
 
-	err := b.Run()
+	result, err := b.Run()
+
+	if err != nil {
+		fmt.Println(err)
+		return 1
+	}
+
+	if !writeExecutable {
+		return 0
+	}
+
+	path := b.Executable()
+	code, data := build.Finalize(result)
+	err = build.Write(path, code, data)
 
 	if err != nil {
 		fmt.Println(err)

src/cli/Help.go

@@ -6,7 +6,7 @@ import "fmt"
 func Help(args []string) int {
 	fmt.Println("Usage: q [command] [options]")
 	fmt.Println("")
-	fmt.Println("    build [directory]")
+	fmt.Println("    build [directory] [file]")
 	fmt.Println("    system")
 	return 2
 }

src/cli/Main_test.go

@@ -1,8 +1,6 @@
 package cli_test
 
 import (
-	"fmt"
-	"os"
 	"testing"
 
 	"git.akyoto.dev/cli/q/src/cli"
@@ -19,17 +17,16 @@ func TestCLI(t *testing.T) {
 		{[]string{}, 2},
 		{[]string{"invalid"}, 2},
 		{[]string{"system"}, 0},
-		{[]string{"build", "non-existing-directory"}, 1},
-		{[]string{"build", "../../examples/hello/hello.q"}, 1},
+		{[]string{"build", "invalid-directory"}, 1},
+		{[]string{"build", "--invalid-parameter"}, 2},
 		{[]string{"build", "../../examples/hello", "--invalid"}, 2},
 		{[]string{"build", "../../examples/hello", "--dry"}, 0},
 		{[]string{"build", "../../examples/hello", "--dry", "--verbose"}, 0},
+		{[]string{"build", "../../examples/hello/hello.q", "--dry"}, 0},
 	}
 
 	for _, test := range tests {
 		t.Log(test.arguments)
-		directory, _ := os.Getwd()
-		fmt.Println(directory)
 		exitCode := cli.Main(test.arguments)
 		assert.Equal(t, exitCode, test.expectedExitCode)
 	}

src/errors/Base.go

@@ -0,0 +1,11 @@
+package errors
+
+// Base is the base class for errors that have no parameters.
+type Base struct {
+	Message string
+}
+
+// Error generates the string representation.
+func (err *Base) Error() string {
+	return err.Message
+}

src/errors/Error.go

@@ -0,0 +1,67 @@
+package errors
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// Error is a compiler error at a given line and column.
+type Error struct {
+	Path   string
+	Line   int
+	Column int
+	Err    error
+	Stack  string
+}
+
+// New generates an error message at the current token position.
+// The error message is clickable in popular editors and leads you
+// directly to the faulty file at the given line and position.
+func New(err error, path string, tokens []token.Token, cursor int) *Error {
+	var (
+		lineCount = 1
+		lineStart = -1
+	)
+
+	for i := range cursor {
+		if tokens[i].Kind == token.NewLine {
+			lineCount++
+			lineStart = int(tokens[i].Position)
+		}
+	}
+
+	var column int
+
+	if cursor < len(tokens) {
+		column = tokens[cursor].Position - lineStart
+	} else {
+		lastToken := tokens[len(tokens)-1]
+		column = lastToken.Position - lineStart + len(lastToken.Text())
+	}
+
+	return &Error{path, lineCount, column, err, Stack()}
+}
+
+// Error generates the string representation.
+func (e *Error) Error() string {
+	path := e.Path
+	cwd, err := os.Getwd()
+
+	if err == nil {
+		relativePath, err := filepath.Rel(cwd, e.Path)
+
+		if err == nil {
+			path = relativePath
+		}
+	}
+
+	return fmt.Sprintf("%s:%d:%d: %s\n\n%s", path, e.Line, e.Column, e.Err, e.Stack)
+}
+
+// Unwrap returns the wrapped error.
+func (e *Error) Unwrap() error {
+	return e.Err
+}

src/errors/Error_test.go

@@ -0,0 +1,32 @@
+package errors_test
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"git.akyoto.dev/cli/q/src/build"
+	"git.akyoto.dev/cli/q/src/errors"
+	"git.akyoto.dev/go/assert"
+)
+
+func TestErrors(t *testing.T) {
+	tests := []struct {
+		File          string
+		ExpectedError error
+	}{
+		{"ExpectedFunctionParameters.q", errors.ExpectedFunctionParameters},
+		{"ExpectedFunctionDefinition.q", errors.ExpectedFunctionDefinition},
+	}
+
+	for _, test := range tests {
+		name := strings.TrimSuffix(test.File, ".q")
+
+		t.Run(name, func(t *testing.T) {
+			b := build.New(filepath.Join("testdata", test.File))
+			_, err := b.Run()
+			assert.NotNil(t, err)
+			assert.Contains(t, err.Error(), test.ExpectedError.Error())
+		})
+	}
+}

src/errors/ScanErrors.go

@@ -0,0 +1,11 @@
+package errors
+
+var (
+	MissingBlockStart          = &Base{"Missing '{'"}
+	MissingBlockEnd            = &Base{"Missing '}'"}
+	MissingGroupStart          = &Base{"Missing '('"}
+	MissingGroupEnd            = &Base{"Missing ')'"}
+	ExpectedFunctionName       = &Base{"Expected function name"}
+	ExpectedFunctionParameters = &Base{"Expected function parameters"}
+	ExpectedFunctionDefinition = &Base{"Expected function definition"}
+)

src/errors/Stack.go

@@ -0,0 +1,30 @@
+package errors
+
+import (
+	"runtime"
+	"strings"
+)
+
+// Stack generates a stack trace.
+func Stack() string {
+	var (
+		final  []string
+		buffer = make([]byte, 4096)
+		n      = runtime.Stack(buffer, false)
+		stack  = string(buffer[:n])
+		lines  = strings.Split(stack, "\n")
+	)
+
+	for i := 6; i < len(lines); i += 2 {
+		line := strings.TrimSpace(lines[i])
+		space := strings.LastIndex(line, " ")
+
+		if space != -1 {
+			line = line[:space]
+		}
+
+		final = append(final, line)
+	}
+
+	return strings.Join(final, "\n")
+}

src/errors/testdata/ExpectedFunctionDefinition.q

@@ -0,0 +1 @@
+main()

src/errors/testdata/ExpectedFunctionParameters.q

@@ -0,0 +1 @@
+main