Syntax tree now stores map of require names -> full paths

parser/accessors.go

@@ -15,6 +15,14 @@ func (tree SyntaxTree) Sections () (iterator types.Iterator[Section]) {
 	return
 }
 
+// ResolveRequire returns the full path, from the filesystem root, of an import.
+// This method will return false for exists if the module has not been
+// imported.
+func (tree SyntaxTree) ResolveRequire (name string) (path string, exists bool) {
+	path, exists = tree.requires[name]
+	return
+}
+
 // Kind returns the section's kind (SectionKindType).
 func (section TypeSection) Kind () (kind SectionKind) {
 	kind = SectionKindType

parser/meta.go

@@ -1,10 +1,14 @@
 package parser
 
+import "os"
+import "path/filepath"
 import "git.tebibyte.media/arf/arf/lexer"
 import "git.tebibyte.media/arf/arf/infoerr"
 
 // parseMeta parsese the metadata header at the top of an arf file.
 func (parser *ParsingOperation) parseMeta () (err error) {
+	cwd, _ := os.Getwd()
+	
 	for {
 		err = parser.expect (
 			lexer.TokenKindName,
@@ -31,7 +35,30 @@ func (parser *ParsingOperation) parseMeta () (err error) {
 		case "license":
 			parser.tree.license = value
 		case "require":
-			parser.tree.requires = append(parser.tree.requires, value)
+			// if import path is relative, get absolute path.
+			if value[0] == '.' {
+				value = filepath.Join(cwd, value)
+			} else if value[0] != '/' {
+				// TODO: get arf import path from an env
+				// variable, and default to this if not found.
+				// then, search all paths.
+				value = filepath.Join (
+					"/usr/local/include/arf/",
+					value)
+			}
+
+			basename  := filepath.Base(value)
+			_, exists := parser.tree.requires[basename]
+
+			if exists {
+				err = parser.token.NewError (
+					"cannot require \"" + basename +
+					"\" multiple times",
+					infoerr.ErrorKindError)
+				return
+			}
+
+			parser.tree.requires[basename] = value
 		default:
 			parser.token.NewError (
 				"unrecognized metadata field: " + field,

parser/meta_test.go

@@ -1,14 +1,18 @@
 package parser
 
+import "os"
 import "testing"
+import "path/filepath"
 
 func TestMeta (test *testing.T) {
+	cwd, _ := os.Getwd()
 	checkTree ("../tests/parser/meta", false,
 `:arf
 author "Sasha Koshka"
 license "GPLv3"
-require "someModule"
+require "` + filepath.Join(cwd, "./some/local/module") + `"
-require "otherModule"
+require "/some/absolute/path/to/someModule"
+require "/usr/include/arf/someLibraryInstalledInStandardLocation"
 ---
 `, test)
 }

parser/parser.go

@@ -38,6 +38,7 @@ func Fetch (modulePath string, skim bool) (tree SyntaxTree, err error) {
 		modulePath: modulePath,
 		skimming:   skim,
 		tree: SyntaxTree {
+			requires: make(map[string] string),
 			sections: make(map[string] Section),			
 		},
 	}

parser/tree.go

@@ -4,8 +4,6 @@ import "git.tebibyte.media/arf/arf/file"
 import "git.tebibyte.media/arf/arf/types"
 import "git.tebibyte.media/arf/arf/infoerr"
 
-// TODO: implement table of import names -> full paths from /. perhaps replace
-// requires[] with this, and build it when parsing the meta section.
 // SyntaxTree represents an abstract syntax tree. It covers an entire module. It
 // can be expected to be syntactically correct, but it might not be semantically
 // correct (because it has not been analyzed yet.)
@@ -13,7 +11,7 @@ type SyntaxTree struct {
 	license string
 	author  string
 
-	requires []string
+	requires map[string] string
 	sections map[string] Section
 }
 

tests/parser/meta/meta.arf

@@ -1,6 +1,7 @@
 :arf
 author "Sasha Koshka"
 license "GPLv3"
-require "someModule"
+require "./some/local/module"
-require "otherModule"
+require "/some/absolute/path/to/someModule"
+require "someLibraryInstalledInStandardLocation"
 ---