Introduce query language (resembling reprepro syntax).

query/syntax.go

@@ -0,0 +1,164 @@
+package query
+
+import (
+	"fmt"
+	"github.com/smira/aptly/deb"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+type parser struct {
+	name  string // used only for error reports.
+	input *lexer // the input lexer
+	err   error  // error stored while parsing
+}
+
+func parse(input *lexer) (PackageQuery, error) {
+	p := &parser{
+		name:  input.name,
+		input: input,
+	}
+	query := p.parse()
+	if p.err != nil {
+		return nil, p.err
+	}
+	return query, nil
+}
+
+// Entry into parser
+func (p *parser) parse() PackageQuery {
+	defer func() {
+		if r := recover(); r != nil {
+			p.err = fmt.Errorf("parsing failed: %s", r)
+		}
+	}()
+
+	q := p.Query()
+	if p.input.Current().typ != itemEOF {
+		panic(fmt.Sprintf("unexpected token %s: expecting end of query", p.input.Current()))
+	}
+	return q
+}
+
+// Query := A | A '|' Query
+func (p *parser) Query() PackageQuery {
+	q := p.A()
+	if p.input.Current().typ == itemOr {
+		p.input.Consume()
+		return &OrQuery{L: q, R: p.Query()}
+	}
+	return q
+}
+
+// A := B | B ',' A
+func (p *parser) A() PackageQuery {
+	q := p.B()
+	if p.input.Current().typ == itemAnd {
+		p.input.Consume()
+		return &AndQuery{L: q, R: p.A()}
+	}
+	return q
+}
+
+// B := C | '!' B
+func (p *parser) B() PackageQuery {
+	if p.input.Current().typ == itemNot {
+		p.input.Consume()
+		return &NotQuery{Q: p.B()}
+	}
+	return p.C()
+}
+
+// C := '(' Query ')' | D
+func (p *parser) C() PackageQuery {
+	if p.input.Current().typ == itemLeftParen {
+		p.input.Consume()
+		q := p.Query()
+		if p.input.Current().typ != itemRightParen {
+			panic(fmt.Sprintf("unexpected token %s: expecting ')'", p.input.Current()))
+		}
+		p.input.Consume()
+		return q
+	}
+	return p.D()
+}
+
+func operatorToRelation(operator itemType) int {
+	switch operator {
+	case 0:
+		return deb.VersionDontCare
+	case itemLt:
+		return deb.VersionLess
+	case itemLtEq:
+		return deb.VersionLessOrEqual
+	case itemGt:
+		return deb.VersionGreater
+	case itemGtEq:
+		return deb.VersionGreaterOrEqual
+	case itemEq:
+		return deb.VersionEqual
+	case itemPatMatch:
+		return deb.VersionPatternMatch
+	case itemRegexp:
+		return deb.VersionRegexp
+	}
+	panic("unable to map token to relation")
+}
+
+// D := <field> <condition>
+// field := <package-name> | <field> | $special_field
+func (p *parser) D() PackageQuery {
+	if p.input.Current().typ != itemString {
+		panic(fmt.Sprintf("unexpected token %s: expecting field or package name", p.input.Current()))
+	}
+
+	field := p.input.Current().val
+	p.input.Consume()
+
+	operator, value := p.Condition()
+
+	r, _ := utf8.DecodeRuneInString(field)
+	if strings.HasPrefix(field, "$") || unicode.IsUpper(r) {
+		// special field or regular field
+		return &FieldQuery{Field: field, Relation: operatorToRelation(operator), Value: value}
+	}
+
+	// regular dependency-like query
+	return &DependencyQuery{Dep: deb.Dependency{Pkg: field, Relation: operatorToRelation(operator), Version: value}}
+}
+
+// condition := '(' <operator> value ')' |
+// operator := | << | < | <= | > | >> | >= | = | % | ~
+func (p *parser) Condition() (operator itemType, value string) {
+	if p.input.Current().typ != itemLeftParen {
+		return
+	}
+	p.input.Consume()
+
+	if p.input.Current().typ == itemLt ||
+		p.input.Current().typ == itemGt ||
+		p.input.Current().typ == itemLtEq ||
+		p.input.Current().typ == itemGtEq ||
+		p.input.Current().typ == itemEq ||
+		p.input.Current().typ == itemPatMatch ||
+		p.input.Current().typ == itemRegexp {
+		operator = p.input.Current().typ
+		p.input.Consume()
+	} else {
+		operator = itemEq
+	}
+
+	if p.input.Current().typ != itemString {
+		panic(fmt.Sprintf("unexpected token %s: expecting value", p.input.Current()))
+	}
+	value = p.input.Current().val
+	p.input.Consume()
+
+	if p.input.Current().typ != itemRightParen {
+		panic(fmt.Sprintf("unexpected token %s: expecting ')'", p.input.Current()))
+	}
+	p.input.Consume()
+
+	return
+}