add more tests, fix structs and if-else formatting

Author: quasilyte

go.mod

@@ -2,4 +2,9 @@ module github.com/quasilyte/minformat
 
 go 1.15
 
-require github.com/go-toolsmith/strparse v1.0.0
+require (
+	github.com/go-toolsmith/astcopy v1.0.0
+	github.com/go-toolsmith/astequal v1.0.1 // indirect
+	github.com/go-toolsmith/strparse v1.0.0
+	github.com/google/go-cmp v0.5.6
+)

go.sum

@@ -1,2 +1,11 @@
+github.com/go-toolsmith/astcopy v1.0.0 h1:OMgl1b1MEpjFQ1m5ztEO06rz5CUd3oBv9RF7+DyvdG8=
+github.com/go-toolsmith/astcopy v1.0.0/go.mod h1:vrgyG+5Bxrnz4MZWPF+pI4R8h3qKRjjyvV/DSez4WVQ=
+github.com/go-toolsmith/astequal v1.0.0/go.mod h1:H+xSiq0+LtiDC11+h1G32h7Of5O3CYFJ99GVbS5lDKY=
+github.com/go-toolsmith/astequal v1.0.1 h1:JbSszi42Jiqu36Gnf363HWS9MTEAz67vTQLponh3Moc=
+github.com/go-toolsmith/astequal v1.0.1/go.mod h1:4oGA3EZXTVItV/ipGiOx7NWkY5veFfcsOJVS2YxltLw=
 github.com/go-toolsmith/strparse v1.0.0 h1:Vcw78DnpCAKlM20kSbAyO4mPfJn/lyYA4BJUDxe2Jb4=
 github.com/go-toolsmith/strparse v1.0.0/go.mod h1:YI2nUKP9YGZnL/L1/DLFBfixrcjslWct4wyljWhSRy8=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

go/minformat/minifier.go

@@ -139,6 +139,9 @@ func (m *minifier) printExpr(n ast.Expr) {
 				m.out.WriteByte(',')
 			}
 		}
+		if n.Ellipsis != token.NoPos {
+			m.out.WriteString("...")
+		}
 		m.out.WriteByte(')')
 
 	case *ast.SliceExpr:
@@ -388,6 +391,13 @@ func (m *minifier) printStmt(n ast.Stmt) {
 		}
 		m.printExpr(n.Cond)
 		m.printBlockStmt(n.Body)
+		if n.Else != nil {
+			m.out.WriteString("else")
+			if _, ok := n.Else.(*ast.IfStmt); ok {
+				m.out.WriteByte(' ')
+			}
+			m.printStmt(n.Else)
+		}
 
 	case *ast.BlockStmt:
 		m.printBlockStmt(n)
@@ -486,20 +496,29 @@ func (m *minifier) printGenDecl(n *ast.GenDecl) {
 }
 
 func (m *minifier) printBinaryExpr(n *ast.BinaryExpr) {
+	spaceBeforeY := false
+
 	// Handle `x < -y` and `x - -y`.
 	if n.Op == token.LSS || n.Op == token.SUB {
 		y := leftmostExpr(n.Y)
 		if y, ok := y.(*ast.UnaryExpr); ok && y.Op == token.SUB {
-			m.printExpr(n.X)
-			m.out.WriteString(n.Op.String())
-			m.out.WriteByte(' ')
-			m.printExpr(n.Y)
-			return
+			spaceBeforeY = true
+		}
+	}
+
+	// Handle `x & ^y` so we don't output it as `x&^y`.
+	if n.Op == token.AND {
+		y, ok := n.Y.(*ast.UnaryExpr)
+		if ok && y.Op == token.XOR {
+			spaceBeforeY = true
 		}
 	}
 
 	m.printExpr(n.X)
 	m.out.WriteString(n.Op.String())
+	if spaceBeforeY {
+		m.out.WriteByte(' ')
+	}
 	m.printExpr(n.Y)
 }
 
@@ -553,6 +572,9 @@ func (m *minifier) printFieldList(n *ast.FieldList, sep byte) {
 			m.out.WriteByte(' ')
 		}
 		m.printExpr(field.Type)
+		if field.Tag != nil {
+			m.out.WriteString(field.Tag.Value)
+		}
 		if j != len(n.List)-1 {
 			m.out.WriteByte(sep)
 		}

go/minformat/minifier_test.go

@@ -2,10 +2,20 @@ package minformat
 
 import (
 	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/parser"
 	"go/token"
+	"io/fs"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/go-toolsmith/strparse"
+	"github.com/google/go-cmp/cmp"
 )
 
 func TestMinifyDecl(t *testing.T) {
@@ -20,6 +30,8 @@ func TestMinifyDecl(t *testing.T) {
 		{`type x = int`, `type x=int`},
 		{`type (a [2] int; b [ ]int)`, `type(a [2]int;b []int)`},
 
+		{`type _ struct { x int "struct tag" }`, `type _ struct{x int"struct tag"}`},
+
 		{`const x, y = 1, 2`, `const x,y=1,2`},
 		{`const (x = 1; y = 2)`, `const(x=1;y=2)`},
 		{`const x int = 1`, `const x int=1`},
@@ -78,6 +90,8 @@ func TestMinifyStmt(t *testing.T) {
 
 		{`if cond { return nil }`, `if cond{return nil}`},
 		{`if x := f(); !x { return nil }`, `if x:=f();!x{return nil}`},
+		{`if cond { f(); } else { g(); }`, `if cond{f()}else{g()}`},
+		{`if cond { f(); } else if cond { g(); }`, `if cond{f()}else if cond{g()}`},
 
 		{`switch {default: return 1}`, `switch{default:return 1}`},
 		{`switch tag {case 1, 2: return 0}`, `switch tag{case 1,2:return 0}`},
@@ -151,6 +165,10 @@ func TestMinifyExpr(t *testing.T) {
 		{`[] int`, `[]int`},
 		{`[ 2 ] int`, `[2]int`},
 
+		{`x &^ y`, `x&^y`},
+		{`x & ^y`, `x& ^y`},
+		{`x & (^y)`, `x&(^y)`},
+
 		{`func () `, `func()`},
 		{`func ( int ) (int, int)`, `func(int)(int,int)`},
 		{`func ( int, int ) (int)`, `func(int,int)int`},
@@ -183,6 +201,7 @@ func TestMinifyExpr(t *testing.T) {
 		{`f(1, 2)`, `f(1,2)`},
 		{`f(1, g(2, 3))`, `f(1,g(2,3))`},
 		{`f( 1 )( 2, 3 )`, `f(1)(2,3)`},
+		{`foo(1, args...)`, `foo(1,args...)`},
 
 		{`struct { }`, `struct{}`},
 		{`struct{ int }`, `struct{int}`},
@@ -218,3 +237,69 @@ func TestMinifyExpr(t *testing.T) {
 		}
 	}
 }
+
+func TestGoroot(t *testing.T) {
+	var goroot string
+	{
+		out, err := exec.Command("go", "env", "GOROOT").CombinedOutput()
+		if err != nil {
+			t.Fatal(err)
+		}
+		goroot = strings.TrimSpace(string(out))
+	}
+
+	visitFile := func(filename string) error {
+		fset := token.NewFileSet()
+		fileContents, err := os.ReadFile(filename)
+		if err != nil {
+			return err
+		}
+		f, err := parser.ParseFile(fset, filename, fileContents, 0)
+		if err != nil {
+			return nil
+		}
+		var minified bytes.Buffer
+		if err := Node(&minified, fset, f); err != nil {
+			return err
+		}
+		fset2 := token.NewFileSet()
+		f2, err := parser.ParseFile(fset2, filename, minified.Bytes(), 0)
+		if err != nil {
+			return fmt.Errorf("re-parse minified: %w", err)
+		}
+		if diff := astDiff(f, f2); diff != "" {
+			return fmt.Errorf("minified code produced different AST:\n%s", diff)
+		}
+		return nil
+	}
+
+	srcDir := filepath.Join(goroot, "src")
+	err := filepath.WalkDir(srcDir, func(path string, info fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		if !strings.HasSuffix(info.Name(), ".go") {
+			return nil
+		}
+		if err := visitFile(path); err != nil {
+			return fmt.Errorf("%s: %w", path, err)
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func astDiff(x, y ast.Node) string {
+	var buf bytes.Buffer
+	format.Node(&buf, token.NewFileSet(), x)
+	s1 := buf.String()
+	buf.Reset()
+	format.Node(&buf, token.NewFileSet(), y)
+	s2 := buf.String()
+	return cmp.Diff(s1, s2)
+}