make compiler errors general, and better imports

cli/main.go

@@ -28,17 +28,38 @@ type DirectoryResolver struct {
 	directories []string
 }
 
-func (r *DirectoryResolver) Resolve(path string) (string, error) {
+func (r *DirectoryResolver) Resolve(from, path string) (*core.ImportResult, error) {
+	// relative imports
+	relpath := filepath.Join(filepath.Dir(from), path)
+	if f, err := os.ReadFile(relpath); err == nil {
+		return &core.ImportResult{
+			Source: string(f),
+			Path:   relpath,
+		}, nil
+	}
+
 	for _, d := range r.directories {
 		pth := filepath.Join(d, path)
 		f, err := os.ReadFile(pth)
 
 		if err == nil {
-			return string(f), nil
+			return &core.ImportResult{
+				Source: string(f),
+				Path:   pth,
+			}, nil
+		}
+
+		pth = filepath.Join(pth, "main.ang")
+		f, err = os.ReadFile(pth)
+		if err == nil {
+			return &core.ImportResult{
+				Source: string(f),
+				Path:   pth,
+			}, nil
 		}
 	}
 
-	return "", errors.New("couldn't resolve import")
+	return nil, errors.New("couldn't resolve import")
 }
 
 func (r *DirectoryResolver) IsSame(a, b string) bool {

core/compiler.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 )
@@ -21,8 +20,13 @@ type Compiler struct {
 	stack *Stack[LocalVariable]
 }
 
+type ImportResult struct {
+	Source string
+	Path   string
+}
+
 type ImportsResolver interface {
-	Resolve(path string) (string, error)
+	Resolve(from, path string) (*ImportResult, error)
 	IsSame(a, b string) bool
 }
 
@@ -34,7 +38,7 @@ type LocalVariable struct {
 
 type CompilerError struct {
 	Description string
-	Causer      Node
+	Boundary    Boundary
 	Source      []rune
 	Trace       []string
 }
@@ -51,7 +55,7 @@ func (e CompilerError) Format() string {
 	b.WriteString(e.Description)
 
 	// highlight offending area
-	start, end := e.Causer.Bounds()
+	start, end := e.Boundary.Bounds()
 
 	lineEnd := 0
 	lineStart := 0
@@ -1254,7 +1258,7 @@ func (c *Compiler) addDescend() {
 	c.add(InstructionDescend)
 }
 
-func (c *Compiler) error(msg string, causer Node) CompilerError {
+func (c *Compiler) error(msg string, causer Boundary) CompilerError {
 	return CompilerError{
 		msg,
 		causer,
@@ -1267,34 +1271,34 @@ func (c *Compiler) warn(msg string, causer Node) {
 	c.Warnings = append(c.Warnings, c.error(msg, causer))
 }
 
-func (c *Compiler) resolveImport(path string) error {
+func (c *Compiler) resolveImport(imp Import) error {
+	res, err := c.resolver.Resolve(c.fileStack.Peek(), imp.path)
+	if err != nil {
+		return err
+	}
+
 	// if already imported and available
 	for _, i := range c.imports {
-		if c.resolver.IsSame(path, i) {
+		if c.resolver.IsSame(res.Path, i) {
 			return nil
 		}
 	}
 
 	// stop recursive imports
 	for i := c.fileStack.Current - 1; i >= 0; i-- {
-		if c.resolver.IsSame(path, c.fileStack.items[i]) {
-			return errors.New("recursive import")
+		if c.resolver.IsSame(res.Path, c.fileStack.items[i]) {
+			return c.error("recursive import", imp)
 		}
 	}
 
-	src, err := c.resolver.Resolve(path)
-	if err != nil {
-		return err
-	}
-
-	l := NewLexer(src)
+	l := NewLexer(res.Source)
 	tokens, err := l.Tokenize()
 	if err != nil {
 		return err
 	}
 
-	parser := NewParser(src, append(c.fileStack.Slice(), path), tokens)
-	p, err := parser.Parse(path)
+	parser := NewParser(res.Source, append(c.fileStack.Slice(), res.Path), tokens)
+	p, err := parser.Parse(res.Path)
 	if err != nil {
 		return err
 	}
@@ -1302,7 +1306,7 @@ func (c *Compiler) resolveImport(path string) error {
 	oldSrc := c.source
 
 	// update source for more descriptive errors
-	c.source = []rune(src)
+	c.source = []rune(res.Source)
 	if err := c.Compile(p); err != nil {
 		return err
 	}

core/nodes.go

@@ -15,6 +15,10 @@ type Node interface {
 	Bounds() (Pos, Pos)
 }
 
+type Boundary interface {
+	Bounds() (Pos, Pos)
+}
+
 const (
 	StringNodeType NodeType = iota
 	NumberNodeType

core/parser.go

@@ -93,17 +93,27 @@ func NewParser(source string, trace []string, tokens []Token) *Parser {
 }
 
 type Program struct {
-	Imports []string
+	Imports []Import
 	Block   *BlockNode
 	Path    string
 }
 
+type Import struct {
+	path  string
+	start Pos
+	end   Pos
+}
+
+func (i Import) Bounds() (Pos, Pos) {
+	return i.start, i.end
+}
+
 func (p *Program) String() string {
 	builder := strings.Builder{}
 
 	builder.WriteString("=== Imports ===\n")
 	for _, i := range p.Imports {
-		builder.WriteString(i)
+		builder.WriteString(i.path)
 		builder.WriteString("\n")
 	}
 	builder.WriteString("===============\n")
@@ -114,7 +124,7 @@ func (p *Program) String() string {
 }
 
 func (p *Parser) Parse(path string) (*Program, error) {
-	imports := make([]string, 0)
+	imports := make([]Import, 0)
 
 	// top level statements
 	statements := make([]Node, 0)
@@ -124,11 +134,16 @@ func (p *Parser) Parse(path string) (*Program, error) {
 
 	for int(p.pos) < len(p.tokens) && p.curr.Type != TokenEOF {
 		if p.accept(TokenImport) {
+			start := p.prev.Start
 			if err := p.expect(TokenString, "import requires a path/name to import"); err != nil {
 				return nil, err
 			}
 
-			imports = append(imports, p.prev.Lexeme[1:len(p.prev.Lexeme)-1])
+			imports = append(imports, Import{
+				p.prev.Lexeme[1 : len(p.prev.Lexeme)-1],
+				start,
+				p.prev.Start + p.prev.Length,
+			})
 			continue
 		}
 
@@ -582,7 +597,7 @@ func (p *Parser) condition() (Node, error) {
 
 	p.advance()
 
-	c, err := p.comparison()
+	c, err := p.condition()
 	if err != nil {
 		return left, err
 	}

wasm/wasm.go

@@ -17,18 +17,21 @@ func (r *JsResolver) IsSame(a, b string) bool {
 	return a == b
 }
 
-func (r *JsResolver) Resolve(name string) (string, error) {
+func (r *JsResolver) Resolve(_, name string) (*core.ImportResult, error) {
 	jsv := r.jsResolver.Invoke(name)
 
 	if jsv.Type() == js.TypeUndefined {
-		return "", errors.New("cannot find import with name " + name)
+		return nil, errors.New("cannot find import with name " + name)
 	}
 
 	if jsv.Type() != js.TypeString {
-		return "", errors.New("invalid value for source: " + jsv.String())
+		return nil, errors.New("invalid value for source: " + jsv.String())
 	}
 
-	return jsv.String(), nil
+	return &core.ImportResult{
+		Source: jsv.String(),
+		Path:   name,
+	}, nil
 }
 
 func jsError(err error) interface{} {