1 files changed, 54 insertions, 0 deletions
diff --git a/src/nbc/substitution.lex b/src/nbc/substitution.lex
new file mode 100644
index 0000000..e460121
--- /dev/null
+++ b/src/nbc/substitution.lex
@@ -0,0 +1,54 @@
+type svalue = Tokens.svalue
+type ('a, 'b) token = ('a, 'b) Tokens.token
+type pos = int
+type lexresult = (svalue, pos) token
+type arg = int ref
+fun eof _ = Tokens.EOF (~1, ~1)
+%%
+%full
+%header (functor SubstitutionLexFun (structure Tokens: SubstitutionGrm_TOKENS));
+%arg (nesting);
+%s VARIABLE PARENTHESIZED BRACED;
+text = ([^$] | "\\$")+;
+dollar = "$";
+leftparenthesis = "(";
+rightparenthesis = ")";
+notparenthesis = [^()]+;
+leftbrace = "{";
+rightbrace = "}";
+notbrace = [^{}]+;
+other = [A-Za-z0-9_]+;
+%%
+<INITIAL>{text} => (Tokens.TEXT (yytext, yypos, yypos + size yytext));
+<INITIAL>{dollar} => (YYBEGIN VARIABLE; Tokens.DOLLAR (yypos, yypos + 1));
+<INITIAL>{dollar}{leftparenthesis} => (
+	YYBEGIN PARENTHESIZED
+	; nesting := !nesting + 1
+	; Tokens.LEFT_PARENTHESIS (yypos, yypos + 1)
+);
+<INITIAL>{dollar}{leftbrace} => (
+	YYBEGIN BRACED
+	; nesting := !nesting + 1
+	; Tokens.LEFT_BRACE (yypos, yypos + 1)
+);
+<VARIABLE>{other} => (YYBEGIN INITIAL; Tokens.TEXT (yytext, yypos, yypos + size yytext));
+<PARENTHESIZED>{notparenthesis} => (Tokens.TEXT (yytext, yypos, yypos + size yytext));
+<PARENTHESIZED>{leftparenthesis} => (
+	nesting := !nesting + 1
+	; Tokens.LEFT_PARENTHESIS (yypos, yypos + 1)
+);
+<PARENTHESIZED>{rightparenthesis} => (
+	nesting := !nesting - 1
+	; if !nesting = 0 then YYBEGIN INITIAL else ()
+	; Tokens.RIGHT_PARENTHESIS (yypos, yypos + 1)
+);
+<BRACED>{notbrace} => (Tokens.TEXT (yytext, yypos, yypos + size yytext));
+<BRACED>{leftbrace} => (
+	nesting := !nesting + 1
+	; Tokens.LEFT_BRACE (yypos, yypos + 1)
+);
+<BRACED>{rightbrace} => (
+	nesting := !nesting - 1
+	; if !nesting = 0 then YYBEGIN INITIAL else ()
+	; Tokens.RIGHT_BRACE (yypos, yypos + 1)
+);