WIP: Add formal specification of the language

spec/assignments.sh

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+
+# Single assignment
+var a = "";
+var a = "something";
+var a = "/usr/home/ken";
+var a = "C:\\Users\\Bill";
+var interests = (
+    "plan9"
+    "go"
+    "c"
+    "asm"
+    "scheme"
+);
+
+# MultipleAssign
+var a, b = "1", "2";
+var a, b, c, d, e, ff, ggg, hhhh = "1", "2", "3", "4", "5", "6", "7", "8";
+var A, B = (), ();
+
+var aa, bb = (), ("a" "b");
+
+# MultipleAssign2
+var (a="1");
+
+var (
+    a = ()
+);
+
+var (
+    this = "",
+    is = "",
+    boring = "",
+);
+
+var (
+    localHost = "localhost",
+    targetHost = "victim.tld",
+);
+
+# ExecAssign
+var out <= boom;
+var _, _ <= nuke deploy --location brasilia;
+
+# set assignments
+a = "1";
+a = ();
+a = ("a" "b");
+
+out, sts <= boom --again;

spec/cmd.sh

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+echo
+echo "hello"
+echo "hello" "world"
+echo $name
+ls $path
+ls /etc/passwd
+cat /non-existent-path
+

spec/comments.sh

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+#!/usr/bin/env nash
+
+#!C:\Users\i4k\bin\nash.exe
+
+#        
+
+#@#$%¨&*()_+
+#[[ç[çsçf]~sçaf~]asçf~]lasfasdf~kas~fkasdjfo34utn3y4y34nt78y4283y4t823
+#       
+#ç~~~~][´```{`´´´;;...maslk dlahs hhkHKHHGJKG GJ JKjgjk gjhkg JGJGkjhg13153//*}]

spec/nash.ohm

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+// Formal specification of nash language using ohm PEG
+// For informations about ohm syntax visit the site below:
+// https://github.com/harc/ohm
+
+// There's an interactive Nash's grammar visualizer at:
+// https://ohmlang.github.io/editor/#fca725147857c09bb442be1ce03048e0
+
+// Note: Nash has automatic semicolon insertion, but this isn't defined here
+// to not complicate the grammar spec.
+
+// TODO: rfork, cmd redirections, pipes, import, string-concat
+
+Nash {
+	Block
+		=	Statement*
+
+	Body
+		= "{" Block "}"
+
+	comment
+		= "#" everythingNoNL*
+
+	Comment
+		= comment
+
+	// Syntatic rules named *Internal are only created to code reuse
+	// They're not nash syntax per-se.
+
+	VarStmt (a variable declaration)
+		= "var" AssignInternal stmtEnd
+
+	AssignStmt (an assignment declaration)
+		= AssignInternal stmtEnd
+
+	MultipleAssignStmt
+		= MultipleAssignInternal stmtEnd
+
+	MultipleAssign2Stmt
+		= MultipleAssign2Internal stmtEnd
+
+	AssignInternal
+		 = SingleAssign | MultipleAssignInternal | MultipleAssign2Internal
+
+	SingleAssign
+		= ident (ValueAssign | ExecAssign)
+
+	ValueAssign
+		= "=" VRHS
+
+	VRHS (a value right-hand-side)
+		= Literal | Variable
+
+	ExecAssign
+		= "<=" ExecExpr
+
+	// a, b, c = ...
+	// out, err, status <= 
+	MultipleAssignInternal (a multiple variables assignment)
+		= MLHS (MultipleValueAssignInternal | ExecAssign)
+
+	// a, b, c
+	MLHS (a multiple left hand side)
+		= NonemptyListOf<ident, ",">
+
+	MultipleAssign2Internal (a list of assignments)
+		= "(" NonemptyListOf<SingleAssign, ","> ","? ")"
+
+	MultipleValueAssignInternal
+		= "=" MVRHS
+
+	// "1", "2", (), ("test")
+	MVRHS 
+		= NonemptyListOf<VRHS, ","> ","?
+
+	// ls $path;
+	// ls /etc;
+	CmdStmt (a command statement)
+		= CmdExpr stmtEnd
+
+	CmdExpr
+		= Program ~"(" (Arg|Variable)*
+
+	// An executable expression is a command or function call
+	// echo "hello"
+	// deploy()
+	ExecExpr (an executable expression)
+		= CmdExpr | FuncallExpr
+
+	FuncallStmt (a function call)
+		= FuncallExpr stmtEnd
+
+	FuncallExpr
+		= ident "(" ListOf<Expr, ","> ")"
+
+	// for {}
+	// for i in $lst {}
+	ForStmt (a for statement)
+		= "for" ForClause? Body
+
+	ForClause
+		= ident "in" Variable
+
+	IfStmt (an if statement)
+		= "if" Condition Body ElseStmt?
+
+	ElseStmt
+		= "else" Body
+
+	Condition
+		= Expr logicalOp Expr
+
+	SetenvStmt 
+		= "setenv" AssignInternal stmtEnd
+
+	Expr (an expression)
+		= Variable | Literal | FuncallExpr
+
+	logicalOp (a logical operator)
+		= "==" | "!="
+
+	Indexing
+		= "[" (integer|Variable) "]"
+
+	// $a
+	// $a[0]
+	// $a[$b]
+	Variable
+		= "$" ident Indexing?
+
+	// A program cannot have a keyword name
+	Program (a program)
+		= ~keywords (ident | Arg)
+
+	Arg (an argument)
+		= string | argLiteral
+
+	// /usr/home/ken
+	// C:\Users\Bill
+	argLiteral 
+		= (alnum|pathSeparator|":"|"-")+
+
+	ident  (an identifier)
+		= ( letter | "_" ) (alnum | "_")*
+
+	pathSeparator (a path separator)
+		= "/" | "\\"
+
+	lineTerminator (a line terminator)
+		= "\n" | "\r" | "\u2028" | "\u2029" | "\r\n"
+
+	stmtEnd (end of statement)
+		= end|";"
+
+	// TODO: This list is not complete
+	// TODO: How to use the ~ lookhead to solve this?
+	string 
+		= "\"" (alnum|blank|"\\"|"-"|":"|"/"|".")* "\""
+
+	integer  (a number)
+		= digit+
+
+	Literal (a literal)
+		= string | ListStmt 
+
+	ListStmt
+		= "(" Literal* ")"
+
+	blank 
+		= " " | "\t" | "\n" | "\r"
+
+	// TODO: get rid of this
+	everythingNoNL
+		= (alnum|"_"|"!"|"@"|"#"|"$"|"%"|"¨"|"&"|"*"|"("|")"|"_"|"-"|"+"|"="|
+			"`"|"´"|"["|"{"|"^"|"~"|"]"|"}"|"<"|">"|":"|"?"|"/"|";"|"."|","|"\\"|
+			"|"|"'"|"\""|" ")
+	keywords 
+		= "for" | "var" | "in" | "setenv" | "if" | "rfork" | "import"
+
+	Statement = (comment | VarStmt | AssignStmt | CmdStmt | FuncallStmt | ForStmt |
+					IfStmt | SetenvStmt)
+
+}

spec/spec.js

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+// Validate nash's grammar
+
+var fs = require('fs');
+
+function getExamples(rootDir, cb) {
+    fs.readdir(rootDir, function(err, files) { 
+        var scripts = []; 
+        for (var i = 0; i < files.length; i++) { 
+            var file = files[i]; 
+            if (file.endsWith('.sh')) { 
+                scripts.push(rootDir + '/' + file);                
+            }
+        }
+        cb(scripts);
+    });
+}
+
+var ohm = require('ohm-js');
+var contents = fs.readFileSync('nash.ohm');
+var nashGrammar = ohm.grammar(contents);
+
+// test the grammar of each example
+getExamples(".", function(files) {
+    for (var i = 0; i < files.length; i++) {
+        var file = files[i];
+        var scriptSource = fs.readFileSync(file);
+        var m = nashGrammar.match(scriptSource);
+        if (m.succeeded()) {
+            console.log(file, ": ok");
+        } else {
+            console.error(file, ": fail");
+            //console.error(nashGrammar.trace(scriptSource).toString());
+        }
+    }
+});