parser: implement support for var declarations

The full Go syntax is supported, blocks or line,
mutiple comma separated variables, assignments.
In local and global frame.

1 files changed, 65 insertions, 0 deletions

diff --git a/parser/decl.go b/parser/decl.go
new file mode 100644
index 0000000..fa07c17
--- /dev/null
+++ b/parser/decl.go
@@ -0,0 +1,65 @@
+package parser
+
+import (
+	"errors"
+	"log"
+	"strings"
+
+	"github.com/gnolang/parscan/lang"
+	"github.com/gnolang/parscan/scanner"
+)
+
+func (p *Parser) ParseVar(in Tokens) (out Tokens, err error) {
+	if len(in) < 1 {
+		return out, errors.New("missing expression")
+	}
+	if in[1].Id != lang.ParenBlock {
+		return p.parseVarLine(in[1:])
+	}
+	if in, err = p.Scan(in[1].Block(), false); err != nil {
+		return out, err
+	}
+	for _, lt := range in.Split(lang.Semicolon) {
+		if lt, err = p.parseVarLine(lt); err != nil {
+			return out, err
+		}
+		out = append(out, lt...)
+	}
+	return out, err
+}
+
+func (p *Parser) parseVarLine(in Tokens) (out Tokens, err error) {
+	decl := in
+	var assign Tokens
+	if i := decl.Index(lang.Assign); i >= 0 {
+		assign = decl[i+1:]
+		decl = decl[:i]
+	}
+	var vars []string
+	if _, vars, err = p.parseParamTypes(decl, parseTypeVar); err != nil {
+		if errors.Is(err, missingTypeError) {
+			for _, lt := range decl.Split(lang.Comma) {
+				vars = append(vars, lt[0].Str)
+				// TODO: compute type from rhs
+				p.addSym(unsetAddr, strings.TrimPrefix(p.scope+"/"+lt[0].Str, "/"), nil, symVar, nil, false)
+			}
+		} else {
+			return out, err
+		}
+	}
+	values := assign.Split(lang.Comma)
+	if len(values) == 1 && len(values[0]) == 0 {
+		values = nil
+	}
+	log.Println("ParseVar:", vars, values, len(values))
+	for i, v := range values {
+		if v, err = p.ParseExpr(v); err != nil {
+			return out, err
+		}
+		out = append(out, v...)
+		out = append(out,
+			scanner.Token{Id: lang.Ident, Str: vars[i]},
+			scanner.Token{Id: lang.Assign})
+	}
+	return out, err
+}