a bit of progress in writing the evaluator function

interp/eval.go

@@ -5,12 +5,14 @@ import (
 	"unsafe"
 )
 
+var debug bool = true
+
 var err_num_args *error_t = &error_t{msg: "wrong number of arguments"}
 
 /*
-	   value stack (p.stack)
+	   value stack (p.vstack)
 
-		           <--- SP
+		           <--- SP (p.vsp)
 		    ARG1
 		    ARG0
 		    NAME
@@ -20,48 +22,52 @@ var err_num_args *error_t = &error_t{msg: "wrong number of arguments"}
 */
 
 func (p *process_t) push_cnode_value(val *Cnode_t) error {
-	if p.sp >= cap(p.stack) {
+	if p.vsp >= cap(p.vstack) {
 		return fmt.Errorf("stack full")
 	}
 
-	p.stack[p.sp] = unsafe.Pointer(uintptr(unsafe.Pointer(val)) | 1)
-	p.sp++
+	// TODO: using the last bit won't be compatible with go's GC.
+	// CHANGE to use inteface{} or devise a different scheme...
+	p.vstack[p.vsp] = unsafe.Pointer(uintptr(unsafe.Pointer(val)) | 1)
+	p.vsp++
 	p.ctx.count++
+	fmt.Printf("push_cnode_value = ctx.count => %d\n", p.ctx.count)
 
 	return nil
 }
 
 func (p *process_t) push_string_value(val string) error {
-	if p.sp >= cap(p.stack) {
+	if p.vsp >= cap(p.vstack) {
 		return fmt.Errorf("stack full")
 	}
 
-	p.stack[p.sp] = unsafe.Pointer(&val)
-	p.sp++
+	p.vstack[p.vsp] = unsafe.Pointer(&val)
+	p.vsp++
 	p.ctx.count++
-
+	fmt.Printf("push_string_value = ctx.count => %d\n", p.ctx.count)
 	return nil
 }
 
 func (p *process_t) merge_top_values() error {
 	var new_val string
 
-	if p.sp < 2 {
+	if p.vsp < 2 {
 		return fmt.Errorf("stack corrupt")
 	}
-	new_val = *(*string)(p.stack[p.sp-2]) + *(*string)(p.stack[p.sp-1])
-	p.sp--
-	p.stack[p.sp] = nil
-	p.stack[p.sp-1] = unsafe.Pointer(&new_val)
+	new_val = *(*string)(p.vstack[p.vsp-2]) + *(*string)(p.vstack[p.vsp-1])
+	p.vsp--
+	p.vstack[p.vsp] = nil
+	p.vstack[p.vsp-1] = unsafe.Pointer(&new_val)
 	p.ctx.count--
+	fmt.Printf("merge_top_values = ctx.count => %d\n", p.ctx.count)
 	return nil
 }
 
 func (p *process_t) pop_value() unsafe.Pointer {
 	var v unsafe.Pointer
-	p.sp--
-	v = p.stack[p.sp]
-	p.stack[p.sp] = nil
+	p.vsp--
+	v = p.vstack[p.vsp]
+	p.vstack[p.vsp] = nil
 	return v
 }
 
@@ -78,6 +84,12 @@ func (p *process_t) call() error {
 		proc = proc_if
 	case "puts":
 		proc = proc_puts
+	case "true":
+		proc = proc_true
+	case "false":
+		proc = proc_false
+	case "null":
+		proc = proc_null
 	default:
 		proc = proc_unknown
 	}
@@ -85,11 +97,11 @@ func (p *process_t) call() error {
 }
 
 func (p *process_t) GetCalleeName() *string {
-	return (*string)(p.stack[p.sp-p.ctx.count+1])
+	return (*string)(p.vstack[p.vsp-p.ctx.count+1])
 }
 
 func (p *process_t) GetArg(idx int) unsafe.Pointer {
-	return (p.stack[p.sp-p.ctx.count+2+idx])
+	return (p.vstack[p.vsp-p.ctx.count+2+idx])
 }
 
 func (p *process_t) GetNumArgs() int {
@@ -97,199 +109,242 @@ func (p *process_t) GetNumArgs() int {
 }
 
 func (p *process_t) Return(val string) {
-	p.stack[p.sp-p.ctx.count] = unsafe.Pointer(&val)
+	p.vstack[p.vsp-p.ctx.count] = unsafe.Pointer(&val)
 }
 
-func (p *process_t) push_context(node *Cnode_t) {
-	p.ctx = &context_t{count: 0, parent_ctx: p.ctx, parent_node: node}
+func (p *process_t) push_context(node *Cnode_t, container_node *Cnode_t) {
+	p.ctx = &context_t{count: 0, parent_ctx: p.ctx, parent_node: node, container_node: container_node}
 }
 
-func (p *process_t) pop_context() (node *Cnode_t) {
-	var i int
+func (p *process_t) pop_context(clear_vstack bool) (*Cnode_t, *Cnode_t) {
+	var (
+		i         int
+		node      *Cnode_t
+		container *Cnode_t
+	)
 
 	node = p.ctx.parent_node
+	container = p.ctx.container_node
 
+	if clear_vstack { // TODO: use the conttext type instead... may be able to use container_node.code???
 		// clean up the unused part of the stack
 		for i = 1; i < p.ctx.count; i++ {
-		p.stack[p.sp-p.ctx.count+i] = nil
+			p.vstack[p.vsp-p.ctx.count+i] = nil
 		}
 
 		// pop off the cleaned arguments
-	p.sp -= p.ctx.count - 1 // keep the return value in the stack
+		p.vsp -= p.ctx.count - 1 // keep the return value in the stack
+	}
 	p.ctx = p.ctx.parent_ctx
 
-	if p.ctx != nil {
-		p.ctx.count++ // let the return value be the argument to the caller
+//	if p.ctx != nil {
+//		p.ctx.count++ // let the return value be the argument to the caller
+//	}
+
+	return node, container
+}
+
+func (interp *Interp) dump_vstack(p *process_t) {
+	fmt.Printf("p.VSP => %d\n", p.vsp)
+	for i := 0; i < p.vsp; i++ {
+		x := uintptr(p.vstack[i])
+		if x&1 == 0 {
+			// string value
+			fmt.Printf(" %d => [%s]\n", i, *(*string)(p.vstack[i]))
+		} else {
+			// cnode value
+			fmt.Printf(" %d => cnode %p", i, p.vstack[i]) // TODO: strip 1 off
+		}
 	}
-	return
 }
 
 /*
-stmt
+puts "hello" world
 
-	   text text bracket
-		              stmt: text text
-					  stmt: text TEXT
+	[STMT]
+		[TEXT|puts] [DQUOTE] [TEXT|world]
+	                     [TEXT|hello]
+
+[puts 1 2; puts 1] 999
+
+	[STMT]
+	    [BRACKET] [TEXT|999]
+		   [STMT]
+		      [TEXT|puts] [TEXT|1] [TEXT|2]
+		   [STMT]
+		      [TEXT|puts] [TEXT|1]
+
+"pu[null 1]ts" 10 20
+
+	[STMT]
+	     [DQUOTE] [TEXT|10] [TEXT|20]
+		    [TEXT|pu] [BRACKET] [JOIN] [TEXT|ts] [JOIN]
+			         [STMT]
+					    [TEXT|null] [TEXT|1]
 */
-func (interp *Interp) eval_atom_node(node *Cnode_t) (*string, error) {
+func (interp *Interp) eval_stmt_nodes(container_node *Cnode_t) (*string, error) {
 	var (
 		p          process_t
 		v          *string
-		inode *Cnode_t
+		stmt_node  *Cnode_t
+		upper_node *Cnode_t
+		inner_node *Cnode_t
+		is_stmt    bool
 		err        error
 	)
 
-	p.interp = interp
+	v = new(string) // TODO: change new(string) to a const
 
-	for node != nil {
-		p.push_context(node)
+	p.interp = interp
+	upper_node = container_node
+	stmt_node = upper_node.child // the first statement
+
+	fmt.Printf("START p.sp = %d\n", p.vsp)
+
+	for stmt_node != nil {
+	start_over_0:
+		if stmt_node.code != CNODE_STMT {
+			panic("internal error - not statement node")
+		}
+
+		fmt.Printf("PUSHING CONTEXT.....\n")
+		p.push_context(stmt_node, upper_node)
 		p.push_string_value("") // placeholder for return value
 
-		for inode = node.child; inode != nil; inode = inode.next {
-			switch inode.code {
+		//start_over:
+		inner_node = stmt_node.child
+	resume:
+		for inner_node != nil {
+			//fmt.Printf("handling %d\n", inner_node.code)
+			switch inner_node.code {
 			case CNODE_BRACKET:
-				//p.push_context(inode)
-				//p.push_string_value("")
-				//node =
+				if inner_node.child != nil {
+					upper_node = inner_node
+					stmt_node = upper_node.child
+					if debug {
+						fmt.Printf("going to start over\n")
+						interp.dump_cnodes(stmt_node, true)
+						fmt.Printf("\n--\n")
+					}
+					goto start_over_0
+
+				} else {
+					// no statements inside []. treat it like an empty string
+					p.push_string_value("")
+				}
+
+			case CNODE_DQUOTE:
+				if inner_node.child != nil {
+					fmt.Printf("PUSHING CONTEXT.....\n")
+					p.push_context(stmt_node, inner_node)
+					//p.push_string_value("") // no placeholder for return value is needed
+					inner_node = inner_node.child
+					if debug {
+						fmt.Printf("going to start over\n")
+						interp.dump_cnodes(stmt_node, true)
+						fmt.Printf("\n--\n")
+					}
+					goto resume
+				} else {
+					// no statements inside []. treat it like an empty string
+					p.push_string_value("")
+				}
+
+			case CNODE_BRACE:
+				p.push_cnode_value(inner_node)
 
 			case CNODE_TEXT:
 
-				//fmt.Printf("XXXXXXXXXXXXXXXXXXXx[%s]\n", string(inode.token))
-				err = p.push_string_value(string(inode.token))
+				//fmt.Printf("XXXXXXXXXXXXXXXXXXXx[%s]\n", string(inner_node.token))
+				err = p.push_string_value(string(inner_node.token))
 				if err != nil {
 					goto oops
 				}
-			}
+
+				// TODO: many more types...
+			case CNODE_JOIN:
+				p.merge_top_values()
 			}
 
-		fmt.Printf("CALLING\n")
+			inner_node = inner_node.next
+		}
+
+		if debug {
+			interp.dump_vstack(&p)
+		}
+		//fmt.Printf("p.ctx.parent_node.code %d p.ctx.container_node.code %d CNODE_STMT %d CNODE_DQUOTE %d CNODE_BRACKET %d\n", p.ctx.parent_node.code, p.ctx.container_node.code, CNODE_STMT, CNODE_DQUOTE, CNODE_BRACKET)
+		if p.ctx.container_node.code == CNODE_INIT || p.ctx.container_node.code == CNODE_BRACKET {
+			if debug {
+				fmt.Printf("calling..... [%s]\n", *p.GetCalleeName())
+			}
 			err = p.call()
 			if err != nil {
 				goto oops
 			}
-		if p.ctx.parent_ctx != nil {
-			p.pop_context()
-		}
 
-		node = node.next
-	}
-
-	v = (*string)(p.pop_value())
-	p.pop_context()
-	if p.ctx != nil {
-		err = fmt.Errorf("internal error - dangling process context")
-		goto oops
-	}
-
-	return v, nil
-
-oops:
-	return nil, err
-}
-
-func (interp *Interp) eval_atom_node_old(node *Cnode_t) (*string, error) {
-
-	var (
-		p   process_t
-		v   *string
-		err error
-	)
-
-	p.interp = interp
-	p.push_context(nil)
-	p.push_string_value("") // placeholder for return value
-
-	for node != nil {
-		switch node.code {
-		case CNODE_BRACKET: // this is a container
-			if node.child != nil {
-				p.push_context(node)
-				err = p.push_string_value("") // placeholder for return value
-				if err != nil {
-					goto oops
-				}
-				node = node.child
-				continue
+			is_stmt = true
 		} else {
-				err = p.push_string_value("")
-				if err != nil {
-					goto oops
+			is_stmt = false
+		}
+
+		fmt.Printf("POPPING CONTEXT.....is_stmt[%v]\n", is_stmt)
+		stmt_node, upper_node = p.pop_context(is_stmt)
+		if upper_node != container_node {
+			if debug {
+				fmt.Printf("resuming... %d upper_node.next %p\n", p.vsp, upper_node.next)
+			}
+
+			if upper_node.code != CNODE_BRACKET {
+				inner_node = upper_node.next // as if it hit the bottom of the innner for loop
+				p.ctx.count++; // use return value  on the stack as an argument
+				goto resume
 			}
 		}
 
-		case CNODE_BRACE: // this is a container
-			err = p.push_cnode_value(node)
-			if err != nil {
-				goto oops
+		//fmt.Printf("POPPING VALUE...\n")
+		/*v = (*string)(p.pop_value()) // get the return value of the statement.
+		if debug {
+			interp.dump_vstack(&p)
+		}*/
+		stmt_node = stmt_node.next
+
+		if stmt_node == nil {
+			// go doesn't allow jumping into a block.
+			// let's the put the code here
+			if upper_node != container_node {
+				// the upper node is not the top containing node passed to this function.
+				// the contenxt stack must not be empty in this case.
+				if upper_node.code != CNODE_BRACKET {
+					panic("internal error - invalid cnode type in the context statck")
+				}
+				fmt.Printf("POPPING CONTEXT.....false\n")
+				//stmt_node, upper_node = p.pop_context(false)
+				inner_node = upper_node.next
+				fmt.Printf(">>>>>>>>>>>>>>>>>> vsp %d ctx.count %d\n", p.vsp, p.ctx.count)
+
+				p.ctx.count++; // use the result value as an argument
+				goto resume
 			}
 
-		case CNODE_DQUOTE: // this is a container
-			// TODO: at the feed layer, recompose CNODE_DQUOTE item to
-			// successive ATOM item
-			// "abc $ddd [xx 11]" must be TEXT("abc ") + VAR("ddd") + BRACKET["xx 11"]  without SEP in between
-
-			// this is not right.....
-			if node.child != nil {
-				// TODO:  something is not right here. handle inner stuffs
-				//fmt.Printf("pushing [%s]\n", string(node.child.token))
-				err = p.push_string_value(string(node.child.token))
-			} else {
-				err = p.push_string_value("")
+			fmt.Printf("POPVAL...\n")
+			v = (*string)(p.pop_value()) // get the return value of the statement.
+			if debug {
+				interp.dump_vstack(&p)
 			}
-			if err != nil {
-				goto oops
+			break
 		}
 
-		case CNODE_VAR:
-
-		case CNODE_TEXT:
-			//fmt.Printf("pushing [%s]\n", string(node.token))
-			err = p.push_string_value(string(node.token))
-			if err != nil {
-				goto oops
-			}
-
-		default:
-			err = fmt.Errorf("internal error - non-atom node - %d", node.code)
-			goto oops
-		}
-
-		node = node.next
-	check_end:
-		if node == nil { // reached the last node
-			err = p.call()
-			if err != nil {
-				goto oops
-			}
-			if p.ctx.parent_ctx != nil {
-				node = p.pop_context()
-				if node.seqno > 0 {
-					// merge the top 2 values (return from [] + previous argument)
-					// for instance,  the expression `aa[qq 11]` must product a single word
-					// `aa` concatenated of the result of `qq 11`
-					err = p.merge_top_values()
-					if err != nil {
-						goto oops
-					}
-				}
-				node = node.next
-
-				// take `aa 11 22 [dd [bb cc]]` as an example
-				// after [bb cc] is called, it must call `[dd]`` followed by `aa`.
-				// this goto loop is to handle successive calls when a nested call is the
-				// last argument
-				goto check_end
-			}
+		fmt.Printf("POPVAL...\n")
+		v = (*string)(p.pop_value()) // get the return value of the statement.
+		if debug {
+			interp.dump_vstack(&p)
 		}
 	}
 
-	v = (*string)(p.pop_value())
-	p.pop_context()
-	if p.ctx != nil {
-		err = fmt.Errorf("internal error - dangling process context")
-		goto oops
+	if debug {
+		interp.dump_vstack(&p)
+		fmt.Printf("END p.sp = %d\n", p.vsp)
 	}
-
 	return v, nil
 
 oops:
@@ -304,8 +359,9 @@ func (interp *Interp) eval_arg(p *process_t, pos int) (*string, error) {
 	ptr = uintptr(p.GetArg(pos))
 	if ptr&1 == 1 { // cnode
 		ptr &= ^uintptr(1)
-		interp.dump_cnodes((*Cnode_t)(unsafe.Pointer(ptr)), true)
-		return interp.eval_atom_node((*Cnode_t)(unsafe.Pointer(ptr)).child)
+		//interp.dump_cnodes((*Cnode_t)(unsafe.Pointer(ptr)), true)
+		//return interp.eval_atom_node((*Cnode_t)(unsafe.Pointer(ptr)).child)
+		return interp.eval_stmt_nodes((*Cnode_t)(unsafe.Pointer(ptr)))
 	} else {
 		return (*string)(unsafe.Pointer(ptr)), nil
 	}

interp/pcl.go

@@ -37,12 +37,13 @@ type context_t struct {
 	count          int
 	parent_ctx     *context_t
 	parent_node    *Cnode_t
+	container_node *Cnode_t
 }
 
 type process_t struct {
 	interp *Interp
-	stack  [16]unsafe.Pointer // value stack - TODO: change size
-	sp     int
+	vstack [16]unsafe.Pointer // value stack - TODO: change size
+	vsp    int
 	ctx    *context_t
 }
 
@@ -245,7 +246,8 @@ func (interp *Interp) Execute(node_head *Cnode_t) (*string, error) {
 			break
 		}
 
-		v, err = interp.eval_atom_node(node.child)
+		//v, err = interp.eval_node_child(node.child)
+		v, err = interp.eval_stmt_nodes(node)
 		if err != nil {
 			return nil, err
 		}

interp/proc.go

@@ -70,6 +70,20 @@ func proc_puts(p *process_t) error {
 	return nil
 }
 
+func proc_false(p *process_t) error {
+	p.Return("false")
+	return nil
+}
+func proc_true(p *process_t) error {
+	p.Return("true")
+	return nil
+}
+
+func proc_null(p *process_t) error {
+	p.Return("")
+	return nil
+}
+
 func proc_unknown(p *process_t) error {
 	fmt.Printf("Unknown command - %s\n", *(p.GetCalleeName()))
 	return nil