Support for namelists. Fixes #3.

expand.go

@@ -3,6 +3,7 @@
 package main
 
 import (
+	"regexp"
 	"strings"
 	"unicode/utf8"
 )
@@ -136,18 +137,45 @@ func expandSigil(input string, vars map[string][]string) ([]string, int) {
 	c, w := utf8.DecodeRuneInString(input)
 	var offset int
 	var varname string
+	var namelist_pattern = regexp.MustCompile(`^\s*([^:]+)\s*:\s*([^%]*)%([^=]*)\s*=\s*([^%]*)%([^%]*)\s*`)
 
 	// escaping of "$" with "$$"
 	if c == '$' {
 		return []string{"$"}, 2
+		// match bracketed expansions: ${foo}, or ${foo:a%b=c%d}
 	} else if c == '{' {
 		j := strings.IndexRune(input[w:], '}')
 		if j < 0 {
 			return []string{"$" + input}, len(input)
 		}
-
 		varname = input[w : w+j]
 		offset = w + j + 1
+
+		// is this a namelist?
+		mat := namelist_pattern.FindStringSubmatch(varname)
+		if mat != nil && isValidVarName(mat[1]) {
+			// ${varname:a%b=c%d}
+			varname = mat[1]
+			a, b, c, d := mat[2], mat[3], mat[4], mat[5]
+			values, ok := vars[varname]
+			if !ok {
+				return []string{}, offset
+			}
+
+			pat := regexp.MustCompile(strings.Join([]string{`^\Q`, a, `\E(.*)\Q`, b, `\E$`}, ""))
+			expanded_values := make([]string, len(values))
+			for i, value := range values {
+				value_match := pat.FindStringSubmatch(value)
+				if value_match != nil {
+					expanded_values[i] = strings.Join([]string{c, value_match[1], d}, "")
+				} else {
+					expanded_values[i] = value
+				}
+			}
+
+			return expanded_values, offset
+		}
+		// bare variables: $foo
 	} else {
 		// try to match a variable name
 		i := 0

lex.go

@@ -11,7 +11,7 @@ type tokenType int
 const eof rune = '\000'
 
 // Rune's that cannot be part of a bare (unquoted) string.
-const nonBareRunes = " \t\n\r\\=:#'\""
+const nonBareRunes = " \t\n\r\\=:#'\"$"
 
 // Return true if the string contains whitespace only.
 func onlyWhitespace(s string) bool {
@@ -383,6 +383,14 @@ func lexBareWord(l *lexer) lexerStateFun {
 			l.next()
 			return lexBareWord
 		}
+	} else if c == '$' {
+		c1 := l.peekN(1)
+		if c1 == '{' {
+			return lexBracketExpansion
+		} else {
+			l.next()
+			return lexBareWord
+		}
 	}
 
 	if l.start < l.pos {
@@ -391,3 +399,11 @@ func lexBareWord(l *lexer) lexerStateFun {
 
 	return lexTopLevel
 }
+
+func lexBracketExpansion(l *lexer) lexerStateFun {
+	l.next() // '$'
+	l.next() // '{'
+	l.acceptUntil("}")
+	l.next() // '}'
+	return lexBareWord
+}